diff --git a/README.md b/README.md
index 19851a0..e4fad52 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Overview
 
-This is a simple game (little modified from the first-person template that comes with UE4), meant to demonstrate the BrickGrid plugin (https://github.com/AndrewScheidecker/BrickGame/tree/master/Plugins/BrickGrid/Source/BrickGrid).
+This is a simple game, meant to demonstrate the BrickGrid plugin (https://github.com/AndrewScheidecker/BrickGame/tree/master/Plugins/BrickGrid/Source/BrickGrid).
 
 The BrickGrid plugin adds a component that imitates Minecraft's bricks. The bricks are cubes that may contain some material, arranged in a 3D grid.
 
@@ -8,14 +8,18 @@ Most of the functionality is implemented in plugins, so you can use those plugin
 
 ![ScreenShot](https://raw.githubusercontent.com/AndrewScheidecker/BrickGame/master/Screenshot.jpg)
 
-# Building the source code
+# Engine modification
 
-1. Install UE4.1 (or newer). Thus far I've been using the UE4.1 preview build, built from source.
-2. Right click on the BrickGame.uproject, and select "Generate Visual Studio Projects".
-3. Open the BrickGame.sln that is created, and run the "Development Editor" configuration of the BrickGame project.
+BrickGame is built with a slightly modified branch of Unreal Engine 4.1. The code for the branch is [here](https://github.com/AndrewScheidecker/UnrealEngine/tree/BrickGame). To use this branch to link against BrickGame, clone it locally, and follow the [instructions](https://github.com/AndrewScheidecker/UnrealEngine/blob/BrickGame/README.md) to register the branch for use by the "Generate Visual Studio Projects" command.
 
-# Keys
+The changes are:
+* Light propagation volume is hacked to ignore the ambient occlusion values computed for the bricks, which will only apply to the ambient cubemap.
+* The way the renderer determines which static elements of a primitive are drawn is modified to allow BrickGame to cull back faces for entire chunks before sending anything to the GPU. BrickGame will compile without this change, but it will not benefit from the early backface culling.
 
+# Controls
+
+WASD: Move
+Mouse: Look
 Left Mouse Button: Add a brick of the selected material
 Right Mouse Button: Remove a brick
 Middle Mouse Button: Select the brick material you're aiming at
@@ -29,27 +33,12 @@ F7: Load the game
 Copyright (c) 2014, Andrew Scheidecker
 All rights reserved.
 
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-    * Redistributions of source code must retain the above copyright
-      notice, this list of conditions and the following disclaimer.
-    * Redistributions in binary form must reproduce the above copyright
-      notice, this list of conditions and the following disclaimer in the
-      documentation and/or other materials provided with the distribution.
-    * Neither the name of BrickGame nor the
-      names of its contributors may be used to endorse or promote products
-      derived from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
-DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
-ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+* Neither the name of BrickGame nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 Unreal® is a trademark or registered trademark of Epic Games, Inc. in the United States of America and elsewhere