diff --git a/init.lua b/init.lua
index 8ebadf1..82d5047 100644
--- a/init.lua
+++ b/init.lua
@@ -79,7 +79,7 @@ function getSandboxEnv (name)
 			backward = function(item, inventory) return commands.insert_item(name,item, inventory,4) end,
 			down = function(item, inventory) return commands.insert_item(name,item, inventory,6) end,
 			up = function(item, inventory) return commands.insert_item(name,item, inventory,5) end,
-			forward_down = function() return commands.insert_item(name,item, inventory,7) end,
+			forward_down = function(item, inventory) return commands.insert_item(name,item, inventory,7) end,
 		},
 		
 		take = { -- takes item from inventory and puts it in robot inventory
@@ -99,7 +99,7 @@ function getSandboxEnv (name)
 			backward = function(itemname, inventory,i) return commands.check_inventory(name,itemname, inventory,i,4) end,
 			down = function(itemname, inventory,i) return commands.check_inventory(name,itemname, inventory,i,6) end,
 			up = function(itemname, inventory,i) return commands.check_inventory(name,itemname, inventory,i,5) end,
-			forward_down = function(item, inventory) return commands.check_inventory(name,itemname, inventory,i,7) end,
+			forward_down = function(item, inventory,i) return commands.check_inventory(name,itemname, inventory,i,7) end,
 			self = function(itemname, inventory,i) return commands.check_inventory(name,itemname, inventory,i,0) end,
 		},
 		
@@ -425,10 +425,8 @@ function getSandboxEnv (name)
 		},
 		
 		colorize = core.colorize,
-		tonumber = tonumber,
-		pairs = pairs,
-		ipairs = ipairs,
-		error = error,
+		tonumber = tonumber, pairs = pairs,
+		ipairs = ipairs, error = error, type=type,
 		
 		--_ccounter = basic_robot.data[name].ccounter, -- counts how many executions of critical spots in script
 		
diff --git a/scripts/avl_tree~.lua b/scripts/avl_tree~.lua
new file mode 100644
index 0000000..595ba86
--- /dev/null
+++ b/scripts/avl_tree~.lua
@@ -0,0 +1,175 @@
+-- 1. MEMORY MANAGEMENT using array with addresses
+-- note: this is all done "automatic" in c with malloc
+
+mem = {};
+mem.size = 10; -- how many available addresses in memory for each of internally used arrays
+mem.freestk = {}; -- stack of free addresses in memory
+mem.stkidx = mem.size;
+for i = 1,mem.size do mem.freestk[i]=mem.size-i+1 end -- so: freestk = {memsize, memsize-1,...., 2, 1 } and head is at last one
+
+mem.allocate = function()  -- pop free spot from stack
+	if mem.stkidx>0 then
+		mem.stkidx = mem.stkidx -1
+		return mem.freestk[mem.stkidx+1]
+	end
+end
+
+mem.free = function(addr) -- release spot and mark it as free
+	if mem.stkidx>=mem.size then -- cant release anymore, all is free
+		return
+	end
+	mem.stkidx = mem.stkidx +1;
+	mem.freestk[mem.stkidx ] = addr;
+end
+
+
+-- 2. BALANCED BINARY SEARCH TREES USING POINTERS created with above MEMORY MANAGEMENT
+
+idx = mem.allocate();
+
+tree = {};
+tree.data = { root = 0, count = 0, -- current root, element count
+	left = {0}, parent = {0}, right = {0}, -- links
+	key = {0}, -- value
+	heightl =  {0}, heightr = {0} -- needed for balancing
+	}; 
+-- root: idx of root element, count: how many elements in tree
+-- 6 arrays with data for node stored at address i in memory: 
+-- left[i] == left child, right[i] = right child, parent[i] = parent, key[i] = stored value, if value left[i]== 0 then no left child...
+-- heightl[i] = height of left subtree, heightr[i] = height of right subtree
+-- NOTE: initially a root node is added
+
+tree.insert = function (value)
+	local data = tree.data;
+	local idx = data.root;
+	if data.count == 0 then data.key[idx] = key; data.count = 1 return true end -- just set root key and exit
+	
+	local key; 
+	local cidx; -- child idx
+
+	
+	while (true) do -- insert into tree by walking deeper and doing comparisons
+		
+		key = data.key[idx];
+		if value<key then 
+			cidx = data.left[idx];
+		else
+			cidx = data.right[idx];
+		end
+		
+		if cidx == 0 then -- we hit nonexistent child, lets insert here
+			cidx = mem.allocate();
+			if not cidx then return "out of space" end
+			data.count = data.count+1
+			data.key[cidx] = value;
+			data.parent[cidx]=idx;data.left[cidx]=0;data.right[cidx]=0;
+			data.heightl[cidx]=0;data.heightr[cidx]=0;
+			
+			-- update all heights for parents and find possible violation of balance property
+			local vidx = 0; -- index where violation happens
+			local vdir = 0; -- type of violation:  1: in left tree , 2: in right tree
+			while (idx~=0) do
+				if data.left[idx] == cidx then
+					data.heightl[idx]=data.heightl[idx]+1
+				else
+					data.heightr[idx]=data.heightr[idx]+1;
+				end
+				
+				if data.heightl[idx]>data.heightr[idx]+1 then 
+					vidx = idx; vdir = 1 
+				elseif data.heightr[idx]>data.heightl[idx]+1 then
+					vidx = idx; vdir = 2
+				end
+				
+				cidx = idx; -- set new child
+				idx = data.parent[idx]; -- set new parent
+			end
+			if vidx~=0 then
+				say("violation vidx " .. vidx .. " direction " .. vdir)
+				-- TO DO: apply internal tree rotation to restore balance
+				if vdir == 1 then -- left violation
+					--[[ need to reconnect 3 nodes:
+						  D <- vidx     C
+						 / \           / \
+						C   E   =>    A   D
+					   / \               / \
+					  A   B             B   E
+					CHANGES: 
+						C: new parent is old parent of D, new children are A,D
+						B: new parent D, 
+						D: new parent is C, new children are B,E
+					--]]
+					local Didx = vidx; local Dpar = data.parent[Didx];
+					local Cidx = data.left[Didx];
+					local Bidx = data.right[Cidx];
+					local Aidx = data.left[Cidx];
+					
+					data.parent[Cidx] = Dpar;data.left[Cidx] = Aidx;data.right[Cidx] = Didx;
+					data.parent[Bidx] = Didx;
+					data.parent[Didx] = Cidx;data.left[Didx] = Bidx;
+					
+					
+				else -- right violation
+										--[[ need to reconnect 3 nodes:
+						  B  <-vidx     C
+						 / \           / \
+						A   C   =>    B   E
+					       / \       / \
+					      D   E     A   D
+					CHANGES: 
+						B: new parent C, new children A,D
+						C: new parent is old parent of B, new children are B,E
+						D: new parent is B
+					--]]
+					local Bidx = vidx; local Bpar = data.parent[Bidx];
+					local Cidx = data.right[Bidx];
+					local Didx = data.left[Cidx];
+					
+					data.parent[Bidx] = Cidx;data.right[Bidx] = data.left[Cidx] 
+					data.parent[Cidx] = Bpar;data.left[Cidx] = Bidx;
+					data.parent[Didx] = Bidx;
+				end
+			end
+			
+		else
+		-- we go deeper
+			idx = cidx;
+		end
+	
+	end
+	
+	tree.find = function(value)
+		local idx = data.root;
+		while (idx~=0) do
+			key = data.key[idx];
+			if key == value then return idx end
+			if value<key then 
+				idx = data.left[idx];
+			else
+				idx = data.right[idx];
+			end
+		end
+	end
+	
+	tree.next = function(idx)
+		local right = data.right[idx]; 
+		local nidx = 0;
+		if right~=0 then 
+			--TO DO: smallest idx in right subtree
+		else
+			if data.parent[idx]==0 then
+				return 0
+			end
+		end
+	end
+	
+	tree.remove = function(idx)
+		--TO DO :
+		-- 1.find next element
+		-- put it where idx was and move subtree..
+	end
+	
+	
+	
+	
+end
\ No newline at end of file
diff --git a/scripts/battle_minesweeper.lua b/scripts/battle_minesweeper.lua
new file mode 100644
index 0000000..b1ebc06
--- /dev/null
+++ b/scripts/battle_minesweeper.lua
@@ -0,0 +1,150 @@
+if not data then
+	m=10;n=10;
+	players = {};
+	paused = true
+	
+	turn = 2;
+	t = 0;
+	SIGNUP = 0; GAME = 1; INTERMISSION = 2
+	state = SIGNUP
+	
+	t0 = _G.minetest.get_gametime();spawnpos = self.spawnpos() -- place mines
+	data = {}; 
+	
+	init_game = function()
+		data = {}; minescount = 32
+		for i = 1, minescount do local i = math.random(m); local j = math.random(n); if not data[i] then data[i] = {} end; data[i][j] = 1; end
+		if not data[1] then data[1] = {} end if not data[2] then data[2] = {} end -- create 2x2 safe area
+		data[1][1] = 0;data[1][2] = 0;data[2][1] = 0;data[2][2] = 0;
+		
+		minescount = 0; 
+		for i = 1,m do for j = 1,n do  -- render game
+			if data[i] and data[i][j] == 1 then minescount = minescount + 1 end
+			if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})~="basic_robot:button808080" then
+				keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},2)
+			end
+		end	end
+		keyboard.set({x=spawnpos.x+1,y=spawnpos.y,z=spawnpos.z+1},4) -- safe start spot
+	end
+	
+	get_mine_count = function(i,j)
+		if i<0 or i>m+1 or j<0 or j>n+1 then return 0 end; count = 0
+		for k = -1,1 do	for l = -1,1 do
+				if data[i+k] and data[i+k][j+l] == 1 then count = count +1 end
+		end	end
+		return count
+	end
+	chk_mines = function()
+		local count = minescount;
+		for i=1,m do for j=1,n do 
+		if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})=="basic_robot:buttonFF8080" and data[i] and data[i][j]==1 then
+			count=count-1
+		end
+		end end
+		return count
+	end
+	
+	greeting = function()
+		_G.minetest.chat_send_all(colorize("red","#BATTLE MINESWEEPER : two player battle in minesweeper. say join to play.\nRules: 1. each player has 5 second turn to make a move 2. if you dont make move you lose\n3. if you make move in other player turn you lose. 4. if you hit bomb or mark bomb falsely you lose"))
+	end
+	
+	player_lost = function ()
+		for i=1,#players do
+			local player = _G.minetest.get_player_by_name(players[i]);
+			if player then player:setpos({x=spawnpos.x,y=spawnpos.y+10,z=spawnpos.z}) end
+		end
+		state = INTERMISSION; t = 0
+	end
+	
+	function change_turn()
+		if turn == 1 then 
+			_G.minetest.sound_play("default_break_glass",{pos=spawnpos, max_hear_distance = 100})
+		else
+			_G.minetest.sound_play("note_a",{pos=spawnpos, max_hear_distance = 100})
+		end
+		
+		if paused == false then 
+			say(players[turn] .. " lost : didn't make a move");
+			player_lost()
+		else
+			if turn == 1 then turn = 2 else turn = 1 end
+			self.label("turn " .. turn .. " " .. players[turn])
+			t=0
+			paused = false
+		end
+	end
+	
+	init_game()
+	greeting()
+	self.listen(1)
+end
+
+if state == SIGNUP then
+	speaker,msg = self.listen_msg()
+	if speaker then
+		if msg == "join" then
+			players[#players+1] = speaker;
+			local plist = ""; for i=1,#players do plist = plist .. players[i] .. ", " end
+			_G.minetest.chat_send_all("BATTLE MINESWEEPER, current players : " .. plist)
+			
+			if #players >= 2 then 
+				state = GAME
+				change_turn();
+				keyboard.get(); t=0; 
+				for i = 1, #players do
+					local player = _G.minetest.get_player_by_name(players[i]);
+					if player then player:setpos({x=spawnpos.x,y=spawnpos.y+1,z=spawnpos.z}) end
+				end
+				_G.minetest.chat_send_all(colorize("red","BATTLE MINESWEEPER " .. m .. "x" ..n .. " with " .. minescount .. " mines.\n" .. players[turn] .. " its your move!"))
+			end	
+				
+		end
+	end
+
+elseif state == GAME then
+
+	t = t + 1;
+	if t>5 then -- change of turn
+		change_turn()
+	end
+
+	event = keyboard.get();
+	if event and event.type == 2 and not paused then
+		if event.puncher == players[turn] then
+			local x = event.x - spawnpos.x;local y = event.y - spawnpos.y;local z = event.z - spawnpos.z;
+			if x<1 or x>m or z<1 or z>n then
+			else
+				local ppos = player.getpos(event.puncher)
+				if ppos and math.abs(ppos.x-event.x)<0.5 and math.abs(ppos.z-event.z)<0.5 then -- just mark mine
+					if data[x] and data[x][z] == 1 then 
+						if keyboard.read({x=event.x,y=event.y,z=event.z})~="basic_robot:button808080" then
+							keyboard.set({x=event.x,y=event.y,z=event.z},2) 
+						else
+							keyboard.set({x=event.x,y=event.y,z=event.z},3)
+						end
+					else
+						say(event.puncher .. " lost : marked a bomb where it was none! ");
+						player_lost()
+					end
+				else
+					if data[x] and data[x][z]==1 then
+							_G.minetest.sound_play("tnt_boom",{pos=spawnpos, max_hear_distance = 100})
+							keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},3)
+							say(event.puncher .. " lost : punched a bomb! ");
+							player_lost()
+					else
+						local count = get_mine_count(x,z);
+						if count == 0 then keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},4)
+						else keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},7+count) end
+					end
+				end
+			end
+			paused = true
+		else
+			say(event.puncher .. " lost : played out of his/her turn"); player_lost()
+		end
+	end
+
+elseif state == INTERMISSION then
+	t=t+1; if t> 15 then state = SIGNUP;players = {}; paused = true; init_game(); greeting() end
+end
\ No newline at end of file
diff --git a/scripts/blackbox.lua b/scripts/blackbox.lua
new file mode 100644
index 0000000..d7f0d1c
--- /dev/null
+++ b/scripts/blackbox.lua
@@ -0,0 +1,195 @@
+--black box by rnd, 03/18/2017
+--https://en.wikipedia.org/wiki/Black_Box_(game)
+
+if not data then
+	m=8;n=8;turn = 0; 
+	attempts = 1;
+	
+	self.spam(1);t0 = _G.minetest.get_gametime();
+	spawnpos = self.spawnpos() 
+	data = {};
+	for i = 1,m do data[i]={}; for j = 1,n do data[i][j]=0 end end
+
+	for i=1,4 do -- put in 4 atoms randomly
+	  data[math.random(m)][math.random(n)] = 1
+	end
+	
+	render_board = function(mode) -- mode 0 : render without solution, 1: render solution
+		for i = 1,m do for j = 1,n do -- render game
+			if mode == 0 or data[i][j] == 0 then
+				if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})~="basic_robot:button808080" then
+					keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},2)
+				end
+			else
+				keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},3)
+			end
+		end	end
+	end
+	
+	get_dirl = function(dir)
+		local dirl; -- direction left
+		if dir[1] > 0.5 then dirl = {0,-1} 
+		elseif dir[1] < -0.5 then dirl = {0,1}
+		elseif dir[2] > 0.5 then dirl = {-1,0}
+		elseif dir[2] < -0.5 then dirl = {1,0}
+		end
+		return dirl
+	end
+	
+	read_pos = function(x,z)
+		if x<1 or x>m or z<1 or z>n then return nil end
+		return data[x][z]
+	end
+	
+	newdir = function(x,z,dir) -- where will ray go next
+		local retdir = {dir[1],dir[2]};
+		local xf = x+dir[1]; local zf = z+dir[2] -- forward
+		local dirl = get_dirl(dir)
+		
+		local nodef = read_pos(xf,zf)
+		local nodel = read_pos(xf + dirl[1],zf + dirl[2])
+		local noder = read_pos(xf - dirl[1],zf - dirl[2])
+		if nodef == 1 then
+			retdir = {0,0} -- ray hit something
+		elseif nodel == 1 and noder ~= 1 then
+			retdir = {-dirl[1],-dirl[2]}
+		elseif nodel ~= 1 and noder == 1 then
+			retdir = {dirl[1],dirl[2]}
+		elseif nodel == 1 and noder == 1 then
+			retdir = {-dir[1],-dir[2]}
+		end
+		return retdir
+	end
+	
+	shootray = function(x,z,dir)
+		--say("ray starts " .. x .. " " .. z .. " dir " .. dir[1] .. " " .. dir[2])
+		local xp = x; local zp =  z;
+		local dirp = {dir[1],dir[2]};
+		local maxstep = m*n;
+		
+		for i = 1,maxstep do
+			dirp = newdir(xp,zp,dirp);
+			if dirp[1]==0 and dirp[2]==0 then return -i end -- hit
+			xp=xp+dirp[1];zp=zp+dirp[2];
+			if xp<1 or xp>m or zp<1 or zp>n then return i,{xp,zp} end -- out
+		end
+		return 0 -- hit
+	end
+	
+	count = 0; -- how many letters were used up
+	border_start_ray = function(x,z)
+		local rdir 
+		if x==0 then rdir = {1,0}
+			elseif x == m+1 then rdir = {-1,0}
+			elseif z == 0 then rdir = {0,1}
+			elseif z == n+1 then rdir = {0,-1}
+		end
+		if rdir then
+			local result,out = shootray(x,z,rdir);
+			if result >= 0 then 
+				
+				if out then
+					if out[1]==x and out[2]==z then -- got back where it originated, reflection
+						keyboard.set({x=spawnpos.x+out[1],y=spawnpos.y,z=spawnpos.z+out[2]},1);
+					else
+						if result<=1 then
+							keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},6); -- immediate bounce off
+						else
+							local nodename = "default:obsidian_letter_"..string.char(97+count) .. "u";
+							_G.minetest.set_node(
+							{x=spawnpos.x+out[1],y=spawnpos.y+1,z=spawnpos.z+out[2]},
+							{name = nodename, param2 = 1})
+							_G.minetest.set_node(
+							{x=spawnpos.x+x,y=spawnpos.y+1,z=spawnpos.z+z},
+							{name = nodename, param2 = 1})
+							count = count + 1;
+							keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},4);
+							keyboard.set({x=spawnpos.x+out[1],y=spawnpos.y,z=spawnpos.z+out[2]},4);
+						end
+					end
+				end
+			elseif result<0 then
+				keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},3); -- hit
+			end
+		end
+	end
+	
+	-- initial border loop and marking
+	
+	--render blue border
+	for i = 1,m do keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+0},5) keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+n+1},5) end
+	for j = 1,n do keyboard.set({x=spawnpos.x+0,y=spawnpos.y,z=spawnpos.z+j},5) keyboard.set({x=spawnpos.x+m+1,y=spawnpos.y,z=spawnpos.z+j},5) end
+	
+	for i = 1,m do keyboard.set({x=spawnpos.x+i,y=spawnpos.y+1,z=spawnpos.z+0},0) keyboard.set({x=spawnpos.x+i,y=spawnpos.y+1,z=spawnpos.z+n+1},0) end
+	for j = 1,n do keyboard.set({x=spawnpos.x+0,y=spawnpos.y+1,z=spawnpos.z+j},0) keyboard.set({x=spawnpos.x+m+1,y=spawnpos.y+1,z=spawnpos.z+j},0) end
+
+	
+	z=0 -- bottom
+	for x = 1,m do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	x=m+1 -- right
+	for z = 1,n do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	z=n+1 -- top
+	for x = m,1,-1 do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	x=0 -- left
+	for z = n,1,-1 do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	check_solution = function()
+		for i = 1,m do
+			for j = 1,n do
+				if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j}) == "basic_robot:buttonFF8080" then -- red
+					if data[i][j]~=1 then return false end
+				else
+					if data[i][j]~=0 then return false end
+				end
+			end
+		end	
+		return true
+	end
+	
+	--render board
+	render_board(0)
+	keyboard.set({x=spawnpos.x,y=spawnpos.y,z=spawnpos.z-1},5)
+	
+end
+
+event = keyboard.get();
+if event then
+	local x = event.x - spawnpos.x;local y = event.y - spawnpos.y;local z = event.z - spawnpos.z;
+	if x<1 or x>m or z<1 or z>n then
+		if event.type == 5 then
+			if check_solution() then
+				say("#BLACKBOX : CONGRATULATIONS! " .. event.puncher .. " found all atoms after " .. attempts .. " tries."); self.remove()
+			else
+				say("#BLACKBOX : " .. event.puncher .. " failed to detect atoms after " .. attempts  .. " attempts.")
+				attempts = attempts+1
+			end
+		end
+	else -- interior punch
+			nodetype = 2;
+			if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button808080" then 
+				nodetype = 3  
+			end
+			keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},nodetype);
+	end
+		
+end
+::END::
\ No newline at end of file
diff --git a/scripts/blackbox_game.lua b/scripts/blackbox_game.lua
new file mode 100644
index 0000000..d7f0d1c
--- /dev/null
+++ b/scripts/blackbox_game.lua
@@ -0,0 +1,195 @@
+--black box by rnd, 03/18/2017
+--https://en.wikipedia.org/wiki/Black_Box_(game)
+
+if not data then
+	m=8;n=8;turn = 0; 
+	attempts = 1;
+	
+	self.spam(1);t0 = _G.minetest.get_gametime();
+	spawnpos = self.spawnpos() 
+	data = {};
+	for i = 1,m do data[i]={}; for j = 1,n do data[i][j]=0 end end
+
+	for i=1,4 do -- put in 4 atoms randomly
+	  data[math.random(m)][math.random(n)] = 1
+	end
+	
+	render_board = function(mode) -- mode 0 : render without solution, 1: render solution
+		for i = 1,m do for j = 1,n do -- render game
+			if mode == 0 or data[i][j] == 0 then
+				if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})~="basic_robot:button808080" then
+					keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},2)
+				end
+			else
+				keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},3)
+			end
+		end	end
+	end
+	
+	get_dirl = function(dir)
+		local dirl; -- direction left
+		if dir[1] > 0.5 then dirl = {0,-1} 
+		elseif dir[1] < -0.5 then dirl = {0,1}
+		elseif dir[2] > 0.5 then dirl = {-1,0}
+		elseif dir[2] < -0.5 then dirl = {1,0}
+		end
+		return dirl
+	end
+	
+	read_pos = function(x,z)
+		if x<1 or x>m or z<1 or z>n then return nil end
+		return data[x][z]
+	end
+	
+	newdir = function(x,z,dir) -- where will ray go next
+		local retdir = {dir[1],dir[2]};
+		local xf = x+dir[1]; local zf = z+dir[2] -- forward
+		local dirl = get_dirl(dir)
+		
+		local nodef = read_pos(xf,zf)
+		local nodel = read_pos(xf + dirl[1],zf + dirl[2])
+		local noder = read_pos(xf - dirl[1],zf - dirl[2])
+		if nodef == 1 then
+			retdir = {0,0} -- ray hit something
+		elseif nodel == 1 and noder ~= 1 then
+			retdir = {-dirl[1],-dirl[2]}
+		elseif nodel ~= 1 and noder == 1 then
+			retdir = {dirl[1],dirl[2]}
+		elseif nodel == 1 and noder == 1 then
+			retdir = {-dir[1],-dir[2]}
+		end
+		return retdir
+	end
+	
+	shootray = function(x,z,dir)
+		--say("ray starts " .. x .. " " .. z .. " dir " .. dir[1] .. " " .. dir[2])
+		local xp = x; local zp =  z;
+		local dirp = {dir[1],dir[2]};
+		local maxstep = m*n;
+		
+		for i = 1,maxstep do
+			dirp = newdir(xp,zp,dirp);
+			if dirp[1]==0 and dirp[2]==0 then return -i end -- hit
+			xp=xp+dirp[1];zp=zp+dirp[2];
+			if xp<1 or xp>m or zp<1 or zp>n then return i,{xp,zp} end -- out
+		end
+		return 0 -- hit
+	end
+	
+	count = 0; -- how many letters were used up
+	border_start_ray = function(x,z)
+		local rdir 
+		if x==0 then rdir = {1,0}
+			elseif x == m+1 then rdir = {-1,0}
+			elseif z == 0 then rdir = {0,1}
+			elseif z == n+1 then rdir = {0,-1}
+		end
+		if rdir then
+			local result,out = shootray(x,z,rdir);
+			if result >= 0 then 
+				
+				if out then
+					if out[1]==x and out[2]==z then -- got back where it originated, reflection
+						keyboard.set({x=spawnpos.x+out[1],y=spawnpos.y,z=spawnpos.z+out[2]},1);
+					else
+						if result<=1 then
+							keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},6); -- immediate bounce off
+						else
+							local nodename = "default:obsidian_letter_"..string.char(97+count) .. "u";
+							_G.minetest.set_node(
+							{x=spawnpos.x+out[1],y=spawnpos.y+1,z=spawnpos.z+out[2]},
+							{name = nodename, param2 = 1})
+							_G.minetest.set_node(
+							{x=spawnpos.x+x,y=spawnpos.y+1,z=spawnpos.z+z},
+							{name = nodename, param2 = 1})
+							count = count + 1;
+							keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},4);
+							keyboard.set({x=spawnpos.x+out[1],y=spawnpos.y,z=spawnpos.z+out[2]},4);
+						end
+					end
+				end
+			elseif result<0 then
+				keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},3); -- hit
+			end
+		end
+	end
+	
+	-- initial border loop and marking
+	
+	--render blue border
+	for i = 1,m do keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+0},5) keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+n+1},5) end
+	for j = 1,n do keyboard.set({x=spawnpos.x+0,y=spawnpos.y,z=spawnpos.z+j},5) keyboard.set({x=spawnpos.x+m+1,y=spawnpos.y,z=spawnpos.z+j},5) end
+	
+	for i = 1,m do keyboard.set({x=spawnpos.x+i,y=spawnpos.y+1,z=spawnpos.z+0},0) keyboard.set({x=spawnpos.x+i,y=spawnpos.y+1,z=spawnpos.z+n+1},0) end
+	for j = 1,n do keyboard.set({x=spawnpos.x+0,y=spawnpos.y+1,z=spawnpos.z+j},0) keyboard.set({x=spawnpos.x+m+1,y=spawnpos.y+1,z=spawnpos.z+j},0) end
+
+	
+	z=0 -- bottom
+	for x = 1,m do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	x=m+1 -- right
+	for z = 1,n do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	z=n+1 -- top
+	for x = m,1,-1 do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	x=0 -- left
+	for z = n,1,-1 do 
+		if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button8080FF" then
+			border_start_ray(x,z)
+		end
+	end
+	
+	check_solution = function()
+		for i = 1,m do
+			for j = 1,n do
+				if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j}) == "basic_robot:buttonFF8080" then -- red
+					if data[i][j]~=1 then return false end
+				else
+					if data[i][j]~=0 then return false end
+				end
+			end
+		end	
+		return true
+	end
+	
+	--render board
+	render_board(0)
+	keyboard.set({x=spawnpos.x,y=spawnpos.y,z=spawnpos.z-1},5)
+	
+end
+
+event = keyboard.get();
+if event then
+	local x = event.x - spawnpos.x;local y = event.y - spawnpos.y;local z = event.z - spawnpos.z;
+	if x<1 or x>m or z<1 or z>n then
+		if event.type == 5 then
+			if check_solution() then
+				say("#BLACKBOX : CONGRATULATIONS! " .. event.puncher .. " found all atoms after " .. attempts .. " tries."); self.remove()
+			else
+				say("#BLACKBOX : " .. event.puncher .. " failed to detect atoms after " .. attempts  .. " attempts.")
+				attempts = attempts+1
+			end
+		end
+	else -- interior punch
+			nodetype = 2;
+			if keyboard.read({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z}) == "basic_robot:button808080" then 
+				nodetype = 3  
+			end
+			keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},nodetype);
+	end
+		
+end
+::END::
\ No newline at end of file
diff --git a/scripts/hash_table_implementation.lua b/scripts/hash_table_implementation.lua
new file mode 100644
index 0000000..e2af33d
--- /dev/null
+++ b/scripts/hash_table_implementation.lua
@@ -0,0 +1,108 @@
+if not get_hash then
+
+	get_hash = function(s,p)
+		if not s then return end
+		local h = 0; local n = string.len(s);local m = 4; -- put 4 characters together
+		local r = 0;local i = 0;
+		while i<n do
+			i=i+1;r = 256*r+ string.byte(s,i);
+			if i%m == 0 then h=h+(r%p) r=0 end
+		end
+		if i%m~=0 then h=h+(r%p) end
+		return h%p
+	end
+	
+	
+	hashdb = {}; --array with entries: [hash] = list of possible hits
+	
+	insert = function(key,value)
+		local hash = get_hash(key,10011);
+		local data = hashdb[hash]; if data == nil then hashdb[hash] = {}; data = hashdb[hash] end
+		data[#data+1]={key,value};
+		return hash
+	end
+	
+	lookup = function(key)
+		local hash = get_hash(key,10011);
+		if not hash then return end
+		local data = hashdb[hash];
+		if not data then return nil end
+		for i = 1,#data do
+			if data[i][1]==key then return data[i][2] end
+		end
+		return nil
+	end
+	
+	analyse = function()
+		local count = 0; local maxlen = 0; local maxidx = 1; local n = #hashdb;
+		for i = 1, 10000 do
+			local data = hashdb[i];
+			if data then
+				local length = #data;
+				if length > maxlen then maxlen = length; maxidx = i end
+				count = count + 1
+			end
+		end
+		
+		if maxlen>0 then
+			local data = hashdb[maxidx];
+			say("number of used hash entries is " .. count .. ", average " .. (step/count) .. " entries per hash, "..
+			" max length of list is " .. maxlen .. " at hash ".. maxidx )--.. " : " .. 
+			--string.gsub(_G.dump(data),"\n","")  )
+			
+		end
+	end
+	
+	-- LOAD DICTIONARY WORDS into hashtable
+	
+	lang = "german"
+
+	fname = "F:\\games\\rpg\\minetest-0415server\\mods\\basic_translate\\"..lang;
+	local f = _G.assert(_G.io.open(fname, "r"));local dicts = f:read("*all");f:close()
+
+	step = 0; maxwords = 10000;
+	i=0
+	dict = {}; -- for comparison
+	
+	while(step<maxwords) do
+		
+		step=step+1
+		i1 = string.find(dicts,"\t",i+1)
+		i2 = string.find(dicts,"\n",i+1)
+	
+		if not i2 then break end
+		
+		local word = string.sub(dicts, i+1,i1-1);
+		local tword = string.sub(dicts, i1+1,i2-1);
+    	insert(word, tword) -- load into hashtable
+		dict[word]=tword
+    	i=i2
+	end
+	
+	self.listen(1)
+	self.spam(1)
+	say(step .. " words loaded")
+end
+
+-- handle chat event
+speaker,msg = self.listen_msg()
+
+if msg then
+	if msg == "?*" then
+		local n = 1000000; local msg = "hello"
+		local ret = "";
+		local t1 = os.clock();
+		for i = 1, n do ret = lookup(msg) end; t1 = os.clock()-t1;
+		local t2 = os.clock();
+		for i = 1, n do ret = dict[msg] end
+		t2 = os.clock()-t2;
+		say(t1 .. " " .. t2)
+	
+	elseif msg == "??" then
+		analyse()
+	elseif string.sub(msg,1,1)=="?" then
+		msg = string.sub(msg,2);
+		local ret = lookup(msg);
+		if ret then say("found entry for " .. msg .. " : " .. ret) else say("entry not found") end
+	end
+end
\ No newline at end of file
diff --git a/scripts/messenger.lua b/scripts/messenger.lua
new file mode 100644
index 0000000..a0c7e21
--- /dev/null
+++ b/scripts/messenger.lua
@@ -0,0 +1,38 @@
+if not s then
+	s=0
+	msgsize = 2500;
+	_,text = book.read(1);text = text or "";
+	write_msg = function(sender,msg)
+
+		local newsize = string.len(text)+string.len(msg);
+		if newsize>msgsize then return "messages space exceeded" end
+		text = text .. "\n"..os.date() .. " " .. sender .. ": " .. msg; 
+		book.write(1,"messages",text)
+	end
+
+end
+
+--textarea[X,Y;W,H;name;label;default]
+--button[X,Y;W,H;name;label]
+if s == 0 then
+	players = find_player(4);
+	if players and players[1] then
+		s=1
+		local form = "size[8,4.5]" ..
+		"textarea[0,0;9,4.5;msg;MESSAGE FOR ADMIN;]"..
+		"button_exit[-0.5,4.15;2,1;send;send]"
+		self.show_form(players[1],form)
+	end
+elseif s==1 then
+	sender,fields = self.read_form();
+	if sender then
+		if fields.send then
+			msg = fields.msg;
+			if msg and msg~="" then
+				write_msg(sender,msg);activate.up(1)
+				_G.minetest.chat_send_player(sender,"#mailbot: message has been stored")
+			end
+		end
+		self.remove()
+	end
+end
\ No newline at end of file
diff --git a/scripts/minesweeper.lua b/scripts/minesweeper.lua
new file mode 100644
index 0000000..c34cd71
--- /dev/null
+++ b/scripts/minesweeper.lua
@@ -0,0 +1,72 @@
+if not data then
+	m=10;n=10; minescount = 32;
+	
+	t0 = _G.minetest.get_gametime();
+	data = {}; spawnpos = self.spawnpos() -- place mines
+	for i = 1, minescount do local i = math.random(m); local j = math.random(n); if not data[i] then data[i] = {} end; data[i][j] = 1; end
+	if not data[1] then data[1] = {} end if not data[2] then data[2] = {} end -- create 2x2 safe area
+	data[1][1] = 0;data[1][2] = 0;data[2][1] = 0;data[2][2] = 0;
+	
+	minescount = 0; 
+	for i = 1,m do for j = 1,n do  -- render game
+		if data[i] and data[i][j] == 1 then minescount = minescount + 1 end
+		if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})~="basic_robot:button808080" then
+			keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},2)
+		end
+	end	end
+	keyboard.set({x=spawnpos.x+1,y=spawnpos.y,z=spawnpos.z+1},4) -- safe start spot
+	get_mine_count = function(i,j)
+		if i<0 or i>m+1 or j<0 or j>n+1 then return 0 end; count = 0
+		for k = -1,1 do	for l = -1,1 do
+				if data[i+k] and data[i+k][j+l] == 1 then count = count +1 end
+		end	end
+		return count
+	end
+	chk_mines = function()
+		local count = minescount;
+		for i=1,m do for j=1,n do 
+		if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})=="basic_robot:buttonFF8080" and data[i] and data[i][j]==1 then
+			count=count-1
+		end
+		end end
+		return count
+	end
+	say("minesweeper " .. m .. "x" ..n .. " with " .. minescount .. " mines ")
+	self.label("find all hidden mines! mark mine by standing on top of block and punch,\notherwise it will uncover the block (and possibly explode).")
+		
+end
+
+event = keyboard.get();
+if event then
+	local x = event.x - spawnpos.x;local y = event.y - spawnpos.y;local z = event.z - spawnpos.z;
+	if x<1 or x>m or z<1 or z>n then
+		if x == 0 and z == 1 then 
+			local count = chk_mines(); 
+			if count == 0 then 
+				t0 = _G.minetest.get_gametime() - t0;
+				say("congratulations! " .. event.puncher .. " discovered all mines in " .. t0 .. " s")
+				_G.minetest.add_item({x=spawnpos.x,y=spawnpos.y+1,z=spawnpos.z},_G.itemstack("default:diamond 5")) -- diamond reward
+			else
+				say("FAIL! " .. count .. " mines remaining ")
+			end
+			self.remove()
+		end
+	elseif event.type == 2 then
+		local ppos = player.getpos(event.puncher)
+		if ppos and math.abs(ppos.x-event.x)<0.5 and math.abs(ppos.z-event.z)<0.5 then -- just mark mine
+			if keyboard.read({x=event.x,y=event.y,z=event.z})~="basic_robot:button808080" then
+				keyboard.set({x=event.x,y=event.y,z=event.z},2) 
+			else
+				keyboard.set({x=event.x,y=event.y,z=event.z},3)
+			end
+		else
+			if data[x] and data[x][z]==1 then
+					say("boom! "..event.puncher .. " is dead ");keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},3);self.remove()
+			else
+				local count = get_mine_count(x,z);
+				if count == 0 then keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},4)
+				else keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},7+count) end
+			end
+		end
+	end
+end
\ No newline at end of file
diff --git a/scripts/minesweeper_game.lua b/scripts/minesweeper_game.lua
new file mode 100644
index 0000000..c34cd71
--- /dev/null
+++ b/scripts/minesweeper_game.lua
@@ -0,0 +1,72 @@
+if not data then
+	m=10;n=10; minescount = 32;
+	
+	t0 = _G.minetest.get_gametime();
+	data = {}; spawnpos = self.spawnpos() -- place mines
+	for i = 1, minescount do local i = math.random(m); local j = math.random(n); if not data[i] then data[i] = {} end; data[i][j] = 1; end
+	if not data[1] then data[1] = {} end if not data[2] then data[2] = {} end -- create 2x2 safe area
+	data[1][1] = 0;data[1][2] = 0;data[2][1] = 0;data[2][2] = 0;
+	
+	minescount = 0; 
+	for i = 1,m do for j = 1,n do  -- render game
+		if data[i] and data[i][j] == 1 then minescount = minescount + 1 end
+		if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})~="basic_robot:button808080" then
+			keyboard.set({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j},2)
+		end
+	end	end
+	keyboard.set({x=spawnpos.x+1,y=spawnpos.y,z=spawnpos.z+1},4) -- safe start spot
+	get_mine_count = function(i,j)
+		if i<0 or i>m+1 or j<0 or j>n+1 then return 0 end; count = 0
+		for k = -1,1 do	for l = -1,1 do
+				if data[i+k] and data[i+k][j+l] == 1 then count = count +1 end
+		end	end
+		return count
+	end
+	chk_mines = function()
+		local count = minescount;
+		for i=1,m do for j=1,n do 
+		if keyboard.read({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j})=="basic_robot:buttonFF8080" and data[i] and data[i][j]==1 then
+			count=count-1
+		end
+		end end
+		return count
+	end
+	say("minesweeper " .. m .. "x" ..n .. " with " .. minescount .. " mines ")
+	self.label("find all hidden mines! mark mine by standing on top of block and punch,\notherwise it will uncover the block (and possibly explode).")
+		
+end
+
+event = keyboard.get();
+if event then
+	local x = event.x - spawnpos.x;local y = event.y - spawnpos.y;local z = event.z - spawnpos.z;
+	if x<1 or x>m or z<1 or z>n then
+		if x == 0 and z == 1 then 
+			local count = chk_mines(); 
+			if count == 0 then 
+				t0 = _G.minetest.get_gametime() - t0;
+				say("congratulations! " .. event.puncher .. " discovered all mines in " .. t0 .. " s")
+				_G.minetest.add_item({x=spawnpos.x,y=spawnpos.y+1,z=spawnpos.z},_G.itemstack("default:diamond 5")) -- diamond reward
+			else
+				say("FAIL! " .. count .. " mines remaining ")
+			end
+			self.remove()
+		end
+	elseif event.type == 2 then
+		local ppos = player.getpos(event.puncher)
+		if ppos and math.abs(ppos.x-event.x)<0.5 and math.abs(ppos.z-event.z)<0.5 then -- just mark mine
+			if keyboard.read({x=event.x,y=event.y,z=event.z})~="basic_robot:button808080" then
+				keyboard.set({x=event.x,y=event.y,z=event.z},2) 
+			else
+				keyboard.set({x=event.x,y=event.y,z=event.z},3)
+			end
+		else
+			if data[x] and data[x][z]==1 then
+					say("boom! "..event.puncher .. " is dead ");keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},3);self.remove()
+			else
+				local count = get_mine_count(x,z);
+				if count == 0 then keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},4)
+				else keyboard.set({x=spawnpos.x+x,y=spawnpos.y,z=spawnpos.z+z},7+count) end
+			end
+		end
+	end
+end
\ No newline at end of file
diff --git a/scripts/radix_sort.lua b/scripts/radix_sort.lua
new file mode 100644
index 0000000..6e3462b
--- /dev/null
+++ b/scripts/radix_sort.lua
@@ -0,0 +1,104 @@
+if not integer_sort then
+	-- sorts input according to keys, changes ordering to permutation corresponding to new order
+	integer_sort = function(input, keys, ordering,temp_ordering, m) -- input, keys same length n, m = how many keys,  O(2*n+m)
+
+		local n = #input;
+		local freq = {} -- frequencies of keys
+		local kpos = {} -- position of keys in sorted array
+		
+		for i=1,n do -- count how many occurences - O(n)
+			local key = keys[ordering[i]]+1;
+			freq[key]=(freq[key] or 0)+1
+			temp_ordering[i]=ordering[i];
+		end
+
+		local curpos = 1;kpos[1]=1;
+		for i =1,m-1 do -- determine positions of keys in final sorted array - O(m)
+			curpos = curpos + (freq[i] or 0);
+			kpos[i+1]=curpos -- {2=3, 3 = 6,..., n-1 = 321}
+		end
+
+		-- actually place values here
+		for i = 1,n do -- O(n)
+			local key = keys[temp_ordering[i]]+1;
+			local pos = kpos[key];
+			ordering[pos] = temp_ordering[i];
+			kpos[key]=kpos[key]+1; -- move to next spot for that key place
+		end
+	end
+
+	permutate = function(input,ordering)
+		local output = {};
+		for i =1,#input do
+			output[i] = input[ordering[i]]
+		end
+		return output
+	end
+
+	get_digits = function(Num,d,base) -- number, how many digits, what base
+		local digits = {};
+		local num = Num;
+		local r;
+		for i = 1, d do
+			r = num % base;
+			digits[#digits+1] = r;
+			num = (num-r)/base
+		end
+		return digits
+	end
+	
+	dumparr = function(array)
+		if _G.type(array) ~= "table" then return array end
+		local ret = "{";
+		for i =1,#array-1 do
+			ret = ret ..  dumparr(array[i]) .. ","
+		end
+		ret = ret .. dumparr(array[#array])
+		return ret .. "}"
+	end
+	
+
+	radix_sort = function(input,d,base) -- array of numbers; base is also number of keys = m, d = how many steps of sorting = number of digits for single number
+
+		out = out .."\nRADIX SORT\n\narray to be sorted " .. dumparr(input)
+
+		local n = #input;
+		local ordering = {}; local temp_ordering = {}; for i = 1, n do ordering[i]=i end
+		local keys = {};
+		local keylist = {};
+		for i = 1,n do
+			keylist[i] = get_digits(input[i],d,base)
+		end
+
+		
+		out = out .."\nlist of keys - ".. d .. " digits of base " .. base .. " expansion of numbers : \n" ..
+		dumparr(keylist)
+
+		for step = 1, d do
+			for i =1,n do
+				keys[i] = keylist[i][step];
+			end
+			integer_sort(input, keys, ordering, temp_ordering, base)
+			
+			out = out .."\n"..step .. ". pass integer_sort : "  .. dumparr(permutate(input,ordering))
+		end
+
+		out = out .. "\nradix sort final result : " .. dumparr(permutate(input,ordering))
+
+	end
+
+
+	--input = {"a","b","c","d","e"}
+	--keys =  {5,3,4,1,2}
+	--ordering = {}; temp_ordering = {}; for i = 1, #input do ordering[i]=i end
+	--m=5;
+
+	--integer_sort(input, keys, ordering, temp_ordering,m);
+	--say(string.gsub(_G.dump(ordering),"\n",""))
+	--say(string.gsub(_G.dump(permutate(input,ordering)),"\n",""))
+	out = ""; self.label("")
+
+	input = {23,42,15,8,87};
+	radix_sort(input,5,3) -- d, base
+	self.display_text(out,60,3)
+end
\ No newline at end of file
diff --git a/scripts/serialization.lua b/scripts/serialization.lua
new file mode 100644
index 0000000..806ff08
--- /dev/null
+++ b/scripts/serialization.lua
@@ -0,0 +1,90 @@
+if not itemlist then
+	inv2string = function(name)
+		local inv = _G.minetest.get_player_by_name(name):get_inventory()
+		local list = ""
+		
+		for i = 1,32 do
+			local item = inv:get_stack("main", i):to_string()
+			list = list .. item .. ","
+		end
+		return name .. "," .. list
+	end
+	
+	string2inv = function(str)
+		local i = string.find(str,",");
+		local name = string.sub(str,1,i-1);
+		local step = 0
+		local invlist = {};
+		while i and step < 33 do
+			step = step +1
+			local i1 = string.find(str,",",i+1)
+			if not i1 then break end
+			invlist[#invlist+1]=string.sub(str,i+1,i1-1)
+			i=i1
+		end
+		return name, invlist
+	end
+	
+	array2string = function(array)
+		if _G.type(array) ~= "table" then return array end
+		local ret = "{";
+		for i =1,#array-1 do
+			ret = ret ..  array2string(array[i]) .. ","
+		end
+		ret = ret .. array2string(array[#array])
+		return ret .. "}"
+	end
+	
+	string2array = function(str)
+		if not string.find(str,"{") then return str end
+		local lvl = 1; local n = string.len(str);
+		local i1,i2,count;
+		count = 0;  --1 = {}, 2 = ,
+		local arr = {}; i1 = 2;
+		for i =2,n do
+			local c = string.sub(str,i,i);
+			if c == "{" then 
+				lvl = lvl+1
+			elseif c == "}" then
+				lvl = lvl -1
+			elseif c == "," and lvl == 1 then
+				i2 = i;
+				count = count+1
+				arr[count] = string2array(string.sub(str,i1,i2-1)); i1 = i2+1
+			end
+		end
+		if i1< n then count = count+1 ; arr[count] =  string2array(string.sub(str,i1,n-1)) end
+		return arr
+	end
+	
+	local arr = {{1,{2,4}},{3,4},{0,{2}},-2};
+	--local arr = {1,2,3}
+	self.spam(1)
+	say("original array : ".. string.gsub(_G.dump(arr),"\n","") )
+	local str = array2string(arr);
+	say("array2string : "  .. str)
+	local arr1 = string2array(str);
+	say("string2array: " .. string.gsub(_G.dump(arr1),"\n",""))
+	
+	player = find_player(2);
+	itemlist = {};
+	if player then
+		local list = inv2string(player[1])
+		local name,invlist = string2inv(list)
+		list = "UNIT TEST inv2string\n"..list .. "\nUNIT TEST string2inv\n".. "name = " .. name .."\n".. string.gsub(_G.dump(invlist),"\n","")
+		form = "size[8,8.5]" ..
+		"textarea[0,0;7.75,7.5;list;list;" .. list .. "]";
+		self.show_form(player[1],form)
+	end
+end
+
+sender,fields = self.read_form();
+if sender then
+	if fields.list then
+		if string.sub(fields.list,1,3) == "DCL" then 
+			local sel = tonumber(string.sub(fields.list,5)) or 1
+			say("you selected item " .. itemlist[sel])
+		end
+	end
+  if fields.quit then self.remove() end
+end
\ No newline at end of file
diff --git a/scripts/shop.lua b/scripts/shop.lua
new file mode 100644
index 0000000..d520cf9
--- /dev/null
+++ b/scripts/shop.lua
@@ -0,0 +1,142 @@
+if not s then
+	s=0;item = 1; price =""; buyer = ""
+	_G.minetest.forceload_block(self.pos(),true)
+	_G.basic_robot.data[self.name()].obj:set_properties({nametag = ""})
+	self.listen(1);self.spam(1)
+	shoplist = {};
+	--scan shops:
+	pos = self.pos(); pos.y=pos.y-5; pos.x=pos.x-6
+	pos1 = {x=pos.x-8,y=pos.y-2,z=pos.z-8};pos2 = {x=pos.x+8,y=pos.y+2,z=pos.z+8};
+	local shoppos = _G.minetest.find_nodes_in_area(pos1, pos2, "shop:shop");
+	--say("scanning... i found " .. #shoppos .. " shops ");
+	count = 0
+	for _,p in pairs(shoppos) do
+		local inv = _G.minetest.get_meta(p):get_inventory()
+		local s = inv:get_list("sell");local b = inv:get_list("buy")
+		local k = s[1]:to_string();
+		local v = b[1]:to_string();
+		if (k and k~="") and (v and v~="") then count = count +1 shoplist[count] = {k,v}  end
+	end
+	
+	local f_sort = function(a,b) return a[1]<b[1] end; 
+	table.sort(shoplist,f_sort)
+
+	itemlist = ""; count = 0;
+	shopinventory = {};
+	for k,v in pairs(shoplist) do
+		if v[1] then
+			count = count +1
+			itemlist = itemlist .. string.format("%-5s%-40s%-32s",k,v[1],v[2]) .. ","
+		end
+	end
+	t = 0; ct = 0;	ci = 0
+	say("scanning shops ... completed. Added " .. count .. " items for sale ");
+end
+
+
+ct=ct+1
+if ct%5 == 0 then
+	ct=0
+	ctext = "say #shop to buy";
+	if ci>0 and ci<=count then
+		if shoplist[ci] then
+			iname = shoplist[ci][1];local p=string.find(iname,":");	if p then iname = string.sub(iname,p+1) end
+			sname = shoplist[ci][2];p=string.find(sname,":");	if p then sname = string.sub(sname,p+1) end
+			ctext = "#SHOP ".. ci .."\n" ..iname .. "\nPRICE\n" .. sname
+		end
+		ci=ci+1
+	elseif ci == count+1 then ci=0
+	elseif ci == 0 then ci=1
+	end
+	
+	text = "SHOP ROBOT"..os.date("%x") .."  " .. os.date("%H:%M:%S").. "\n\n"..ctext
+	self.display_text(text,10,3);
+end
+
+speaker,msg = self.listen_msg()
+if msg then
+	if s == 0 then
+		if string.sub(msg,1,5)=="#shop" then
+			if msg == "#shop" then
+				--say("say #shop command, where command is list OR armor OR item number. Example: #shop list or #shop 1")
+				
+				local list = "1,2,3";
+				local form = "size[8,8.5]" ..
+				"label[0.,0.5;ID]"..
+				"label[0.4,0.5;BUY]"..
+				"label[3.,0.5;SELL]" ..
+				"field[7.2,0.25;1.,1;count;count;".. 1 .."]"..
+				"button[5.,-0.05;2.,1;ARMOR;ARMOR]"..
+				"textlist[0,1;7.75,7.5;list;" .. itemlist .. "]";
+				self.show_form(speaker,form)
+			end
+		end
+	elseif s == 1 then 
+		if string.sub(msg,1,3)~="buy" then 
+			t=t+1; if t>1 then say("timeout. trade cancelled."); s = 0 end
+		else
+			
+			
+			s=0
+		end
+	end
+end
+
+sender,fields = self.read_form()
+if sender then
+	local sel = fields.list; --"CHG:3"
+	--say( string.gsub(_G.dump(fields),"\n",""))
+	if sel and string.sub(sel,1,3) == "DCL" then
+		local quantity = tonumber(fields.count) or 1;
+		local select = tonumber(string.sub(sel,5) or "") or 1;
+		local item, price
+		
+		if shoplist[select] then
+			item,price = shoplist[select][1],shoplist[select][2];
+		end
+		
+		local player = _G.minetest.get_player_by_name(sender);
+		if player and item and price then
+			
+			local inv = player:get_inventory();
+			if quantity > 99 then quantity = 99 end
+			if quantity > 1 then
+				local k = 1;
+				local i = string.find(price," ");
+				if i then 
+					k = tonumber(string.sub(price,i+1)) or 1 
+					price = string.sub(price,1,i-1).. " " .. k*quantity
+				else 
+					price = price.. " " .. quantity
+				end
+				
+				k=1;i = string.find(item," ");
+				if i then 
+					k = tonumber(string.sub(item,i+1)) or 1 
+					item = string.sub(item,1,i-1).. " " .. k*quantity
+				else
+					item = item .. " " .. quantity
+				end
+			end
+			
+			if inv:contains_item("main", price ) then 
+				inv:remove_item("main",price)
+				inv:add_item("main",item)
+				_G.minetest.chat_send_player(sender,"#SHOP ROBOT: " .. item .. " sold to " .. sender .. " for " .. price)
+			else 
+				_G.minetest.chat_send_player(sender,"#SHOP ROBOT: you dont have " .. price .. " in inventory ")
+			end
+		end
+	elseif fields.ARMOR then
+		local player = _G.minetest.get_player_by_name(sender);
+		if player then
+			local inv = player:get_inventory();
+			if inv:contains_item("main",_G.ItemStack("default:diamond 30")) then
+				player:set_armor_groups({fleshy = 50})
+				_G.minetest.chat_send_player(sender,"#SHOP ROBOT: you bought 50% damage reduction.")
+			else
+				_G.minetest.chat_send_player(sender,"#SHOP ROBOT: you need 30 diamonds to get armor effect")
+			end
+		end
+	end
+end
\ No newline at end of file
diff --git a/scripts/simple_layout_gen.lua b/scripts/simple_layout_gen.lua
new file mode 100644
index 0000000..802e3a3
--- /dev/null
+++ b/scripts/simple_layout_gen.lua
@@ -0,0 +1,24 @@
+if not data then
+	m=50;n=50; minescount = m*n/10;
+	
+	t0 = _G.minetest.get_gametime();
+	data = {}; spawnpos = self.spawnpos();
+	for i = 1, minescount do local i = math.random(m); local j = math.random(n); if not data[i] then data[i] = {} end; data[i][j] = 1; end
+
+	get_mine_count = function(i,j)
+		if i<0 or i>m+1 or j<0 or j>n+1 then return 0 end; count = 0
+		for k = -1,1 do	for l = -1,1 do
+				if data[i+k] and data[i+k][j+l] == 1 then count = count +1 end
+		end	end
+		return count
+	end
+	
+	for i = 1,m do for j = 1,n do
+		if get_mine_count(i,j) > 0 or (data[i] and data[i][j] == 1) then
+			_G.minetest.swap_node({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j}, {name = "basic_robot:buttonFFFFFF"})
+		else
+			_G.minetest.swap_node({x=spawnpos.x+i,y=spawnpos.y,z=spawnpos.z+j}, {name = "default:dirt"})
+		end
+	end	end
+end
+self.remove()
\ No newline at end of file