a complete development utility for graphics of tile-based games. The application contains a bitmap editor for creating tiles and sprites and a map editor for designing level maps.
a 2D fighting game in the same style as Double Dragon and TMNT. Paintown is very extensible and comes with editors to help design new levels and animations.
With hundreds of published titles, 3D GameStudio authoring suite for 2D, 3D realtime applications. It combines the C-Script programming language with a high-end 3D engine, a 2D engine, a physics engine, a level, terrain and model editor, etc...
a free / freeware open source tool for 2-D game development. It is designed for the Windows 9x/DirectX platform, and targeted at people spanning a range of skill levels.