diff --git a/README.txt b/README.txt
index 87c5e6c..2cb3fee 100644
--- a/README.txt
+++ b/README.txt
@@ -1,4 +1,4 @@
-overgen 0.1.3 by paramat
+overgen 0.2.0 by paramat
 For latest stable Minetest back to 0.4.8
 Depends default
 Licenses: code WTFPL
diff --git a/init.lua b/init.lua
index 3b2295f..7bc62df 100644
--- a/init.lua
+++ b/init.lua
@@ -1,18 +1,19 @@
--- overgen 0.1.3 by paramat
+-- overgen 0.2.0 by paramat
 -- For latest stable Minetest and back to 0.4.8
 -- Depends default
 -- License: code WTFPL
 
--- Speed increase: use LVM for 'ungen' check and scanning chunk below
+-- use VM for ungen check and scanning chunk below
+-- scan to 16 nodes below to initialise stability table 
 
 -- Parameters
 
-local YMIN = 6000 -- Approximate realm base, atmosphere top
-local YMAX = 8000
-local TCEN = 7016 -- Terrain centre, average solid surface level
-local WATY = 7016 -- Water surface y
-local TSCA = 128 -- Terrain scale, approximate average height of hills
-local STOT = 0.04 -- Stone threshold, controls epth of stone below surface
+local YMIN = -2000 -- Approximate realm base
+local YMAX = 1000 -- Approximate atmosphere top
+local TCEN = 1 -- Terrain centre, average solid surface level
+local WATY = 1 -- Water surface y
+local TSCA = 192 -- Terrain scale, approximate average height of hills
+local STOT = 0.03 -- Stone threshold, controls depth of stone below surface
 local STABLE = 2 -- Minimum number of stacked stone nodes in column required to support sand
 
 -- 3D noise for terrain
@@ -20,15 +21,17 @@ local STABLE = 2 -- Minimum number of stacked stone nodes in column required to
 local np_terrain = {
 	offset = 0,
 	scale = 1,
-	spread = {x=256, y=192, z=256}, -- largest scale in nodes
+	spread = {x=384, y=192, z=384}, -- largest scale in nodes
 	seed = 5900033,
 	octaves = 5, -- number of levels of detail
-	persist = 0.67 -- roughness / crazyness, 0.4 = smooth, 0.6 = MT standard
+	persist = 0.63 -- roughness / crazyness, 0.4 = smooth, 0.6 = MT standard
 }
 
 -- Stuff
 
-overgen = {}
+minetest.register_on_mapgen_init(function(mgparams)
+	minetest.set_mapgen_params({mgname="singlenode", water_level=1})
+end)
 
 -- Nodes
 
@@ -48,7 +51,8 @@ minetest.register_on_generated(function(minp, maxp, seed)
 		return
 	end
 
-	local t1 = os.clock()
+	local t0 = os.clock()
+
 	local x1 = maxp.x
 	local y1 = maxp.y
 	local z1 = maxp.z
@@ -71,28 +75,33 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	local c_ovgstone = minetest.get_content_id("overgen:stone")
 	
 	local sidelen = x1 - x0 + 1
-	local chulens = {x=sidelen, y=sidelen+2, z=sidelen}
-	local minpos = {x=x0, y=y0-1, z=z0}
+	local vvii = sidelen + 32
+	local chulens = {x=sidelen, y=sidelen+17, z=sidelen}
+	local minpos = {x=x0, y=y0-16, z=z0}
 	local nvals_terrain = minetest.get_perlin_map(np_terrain, chulens):get3dMap_flat(minpos)
 	
 	local viu = area:index(x0, y0-1, z0)
-	local ungen = data[viu] == c_ignore
+	local ungen = data[viu] == c_ignore -- ungenerated mapchunk below
 	
 	local ni = 1
 	local stable = {}
 	local under = {}
-	for z = z0, z1 do
-		for y = y0 - 1, y1 + 1 do
+	for z = z0, z1 do -- for each vertical plane
+		for x = x0, x1 do -- set initial values of stability table to zero
+			local si = x - x0 + 1 -- stability table index
+			stable[si] = 0
+		end
+		for y = y0 - 16, y1 + 1 do -- for each horizontal row
 			local vi = area:index(x0, y, z)
-			for x = x0, x1 do
+			for x = x0, x1 do -- for each node
 				local si = x - x0 + 1
 				local grad = (TCEN - y) / TSCA
 				local density = nvals_terrain[ni] + grad
-				if y == y0 - 1 then -- node layer below chunk
+				if y < y0 then -- node layers below mapchunk
 					if ungen then
-						if density >= 0 then -- if node solid
-							stable[si] = STABLE
-						else
+						if density >= STOT then -- if node stone
+							stable[si] = stable[si] + 1
+						elseif density < 0 then -- air or water
 							stable[si] = 0
 						end
 					else
@@ -100,35 +109,38 @@ minetest.register_on_generated(function(minp, maxp, seed)
 						if nodid == c_air
 						or nodid == c_water then
 							stable[si] = 0
-						else
-							stable[si] = STABLE
+						elseif nodid == c_ovgstone then
+							stable[si] = stable[si] + 1
 						end
 					end
-				elseif y >= y0 and y <= y1 then
+				elseif y >= y0 and y <= y1 then -- mapchunk
 					if density >= STOT then
 						data[vi] = c_ovgstone
 						stable[si] = stable[si] + 1
 						under[si] = 0
-					elseif density >= 0 and density < STOT and stable[si] >= STABLE then
+					elseif density >= 0 and density < STOT
+					and stable[si] >= STABLE then
 						data[vi] = c_sand
 						under[si] = 1
 					elseif y <= WATY then
 						data[vi] = c_water
 						stable[si] = 0
 						under[si] = 0
-					else -- air, possible above surface node
+					else -- air, possibly above surface
 						data[vi] = c_air
 						if under[si] == 1 then -- if air above surface node
-							local viu = area:index(x, y-1, z) -- index of 'under' node
+							local viu = vi - vvii -- index of 'under' node
 							data[viu] = c_desand -- replace node below with surface node
 						end
 						stable[si] = 0
 						under[si] = 0
 					end
-				elseif y == y1 + 1 then -- plane of nodes above chunk
-					if density < 0 and under[si] == 1 and y >= WATY + 1 then -- if air above surface 
-						local viu = area:index(x, y-1, z)
-						data[viu] = c_desand -- replace node below with surface node
+				elseif y == y1 + 1 then -- layer of nodes above mapchunk
+					if density < 0 and y > WATY then -- air, possibly above surface
+						if under[si] == 1 then -- if air above surface node
+							local viu = vi - vvii -- index of 'under' node
+							data[viu] = c_desand -- replace node below with surface node
+						end
 					end
 				end
 				ni = ni + 1 -- increment perlinmap noise index
@@ -141,6 +153,8 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	vm:set_lighting({day=0, night=0})
 	vm:calc_lighting()
 	vm:write_to_map(data)
-	local chugent = math.ceil((os.clock() - t1) * 1000)
+	--vm:update_liquids()
+
+	local chugent = math.ceil((os.clock() - t0) * 1000)
 	print ("[overgen] "..chugent.." ms")
 end)