Game Creation Software
Easily make HTML5 games for a variety of platforms with Construct 2.

Open source game creation software with no programming or coding required. Make HTML5 for several platforms.

Make 2D games with Gamemaker.

Garage Games
GarageGames provides game development tools and software including the Torque 3D game engine, Torque 2D game engine, Torque game engine for iPhone, and Torque game engine for consoles. Torque is also used by a multitude of game design and development educational institutions that allow students to learn how to make games.

YoYo Games
A resource for creating your own games. You can download Gamemaker 7, which allows you to make your own 2 dimensional video games, find game sound and graphic downloads, participate in the game maker community forum, as well as play games on the site.

FlashPunk is a free ActionScript 3 library designed for developing 2D flash games.

An AS3 resource for making your own flash games.

FlashDevelop is an open source ActionScript 2/3 and Web development environment.