From BlenderWiki

User Documentation and help

• Introduction to the Blender Game Engine (Tutorial)
• Lots of External tutorials
• Frequently Asked Questions (FAQ) about the Blender Game Engine

• Original Blender GameKit
• Using Material GLSL Material Shaders
• Game Engine Tutorials in wiki format

In development:

• Blender GameKit 2.0
• Blender Game Engine User Manual

Game Development tools and utilities

• GIMP - GPL Image Manipulation Program on Linux and Windows
• IconArt - make custom icons for your game.exe
• Setup2go and Installer2go - installer creators
• Inno Setup - a very good free installer
• BZoo - a powerful network game template
• Game Engine Competition

Forums and Chat

• forums (offline help)
• irc (online help and developer forum)

Developer Documentation

• GameEngineDev
• bug tracker

Documentation Writer's Guide

• To-Do List of GE features needing end-user documentation
• List of topics that are about the Game Engine (GE)

Reference and Related documentation

Many games include an Artificial Intelligence program that makes things react and move and change state as the game is played. Python is the language in which the AI engine is written, and runs inside the BGE.

• Python, the scripting language
• Python docs for beginner

Game Engine Python API docs

• Game Logic Python API for Blender 2.34
• Game engine GLSL python APi
• Bullet physics Python API ?