diff --git a/_data/links.yml b/_data/links.yml
index 7e9c82d..9fa7967 100644
--- a/_data/links.yml
+++ b/_data/links.yml
@@ -25,18 +25,22 @@
 
 - hr: true
 
-- title: Formspecs
+- title: Player Physics
   num:   6
+  link:  chapters/player_physics.html
+
+- title: Formspecs
+  num:   7
   link:  chapters/formspecs.html
 
 - title: HUD
-  num:   7
+  num:   8
   link:  chapters/hud.html
 
 - hr: true
 
 - title: Releasing a Mod
-  num: 8
+  num: 9
   link: chapters/releasing.html
 
 - hr: true
diff --git a/chapters/abms.md b/chapters/abms.md
index 0228a98..e9da473 100644
--- a/chapters/abms.md
+++ b/chapters/abms.md
@@ -14,6 +14,7 @@ Please be warned, ABMs which are too frequent or act on too many nodes cause
 massive amounts of lag. Use them lightly.
 
 * Special Growing Grass
+* Your Turn
 
 Special Growing Grass
 ---------------------
@@ -49,8 +50,8 @@ blocks above grass blocks - you should check there is space by doing minetest.ge
 
 That's really all there is to ABMs. Specifying a neighbor is optional, so is chance.
 
-Tasks
------
+Your Turn
+---------
 
 * **Midas touch**: Make water turn to gold blocks with a 1 in 100 chance, every 5 seconds.
 * **Decay**: Make wood turn into dirt when water is a neighbor.
diff --git a/chapters/player_physics.md b/chapters/player_physics.md
new file mode 100644
index 0000000..d8e2572
--- /dev/null
+++ b/chapters/player_physics.md
@@ -0,0 +1,65 @@
+---
+title: Player Physics
+layout: default
+root: ../
+---
+
+Introduction
+------------
+
+Player physics can be modified using physics overrides. Physics overrides can set the
+walking speed, jump speed and gravity constants. Physics overrides are set on a player
+by player basis, and are multipliers - a value of 2 for gravity would make gravity twice
+as strong.
+
+* Basic Interface
+* Your Turn
+
+Basic Interface
+---------------
+
+Here is an example which adds an antigravity command, which
+puts the caller in low G:
+
+{% highlight lua %}
+minetest.register_chatcommand("antigravity",
+	func = function(name, param)
+		local player = minetest.get_player_by_name(name)
+		player:set_physics_override({
+			gravity = 0.1 -- set gravity to 10% of its original value
+			              -- (0.1 * 9.81)
+		})
+	end
+})
+{% endhighlight %}
+
+### Possible Overrides
+
+player:set_physics_override() is given a table of overrides.\\
+According to [lua_api.txt](lua_api.html#player-only-no-op-for-other-objects),
+these can be:
+
+* speed: multiplier to default walking speed value (default: 1)
+* jump: multiplier to default jump value (default: 1)
+* gravity: multiplier to default gravity value (default: 1)
+* sneak: whether player can sneak (default: true)
+* sneak_glitch: whether player can use the sneak glitch (default: true)
+
+The sneak glitch allows the player to climb an 'elevator' made out of
+a certain placement of blocks by sneaking (pressing shift) and pressing
+space to ascend. It was originally a bug in Minetest, but was kept as
+it is used on many servers to get to higher levels.
+They added the option above so you can disable it.
+
+### Multiple mods
+
+Please be warned that mods that override the physics of a player tend
+to be incompatible with each other. When setting an override, it overwrites
+and override that has been set before, by your or anyone else's mod.
+
+Your Turn
+---------
+
+* **sonic**: Set the speed multiplayer to a high value (at least 6) when a player joins the game.
+* **super bounce**: Increase the jump value so that the player can jump up 20 meters (1 meter is 1 block).
+* **space**: Make the gravity decrease the the player gets higher and higher up.