2D game development library for Ruby and C++
LÖVE is an awesome 2D game framework for Lua
Enigma is a puzzle game
Delphi : VRCalc++ OOSL & + (Paged List, TextEditor, VRAstroVision ...)
A free 3D game engine to create games and realtimes scenes for Windows
2D Open Source MMORPG
A cross-platform 2D game engine
Free and Open Game Programming Language for Windows and GNU/Linux
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons
Free/Open Source 2D Arcade Golf Game
2D game engine for traditional platform games
A traditional top-down OpenGL car racing game
A team-oriented tank shooter game.
2D physics engine for games
Free 2D top-down scrolling SHMUP Game
Cross platform 2D game creation framework with Python bindings
3D game engine for C and C++
The solution to all your problems
KPEdit - A 2D skeletal animation editor.
Free 2D SHMUP Game
2D Multi-directional Shooter
easy programming language for 2d games
Delphi-like IDE for cross-platform game development