Resources
Create low-poly humans easily for use in the Blender Game Engine with this simple template. Model is textured, rigged, and simple to modify. Unfortunately it's also really hideous, but it's still a better alternative than decimating MakeHuman models (which is a really bad method). Hopefully soon I'll have a chance to take a look at this thing again and improve it so that it will be more useful.

Learn how to create realistic environments for the Blender Game Engine with this lengthy tutorial. Download the example file.

 

You can use this set of scripts to create a game in which you click on part of a landscape and a character will travel to that position. Useful for strategy, RPG and other overhead-view games. Note that this is not intelligent pathfinding: the character will attempt to take the shortest route possible, regardless of whether it makes any sense.

A script which allows the user to set up mouse-selectable objects in the Blender Game Engine. Selection status is stored in a Boolean property for easy access.
Learn to make functional binoculars for the Blender Game Engine with this tutorial.
Learn to use thumbnailing to improve the quality of your concept designs.

Discusses game concepts and their application in my game Into the Titan.