CTFs as you need them
Desktop/Android/HTML5/iOS Java game development framework
Open source library for N64 development
One framework for creating powerful cross-platform games
Self-hosted CMS platform based on the Laravel PHP Framework
Open source library for creative expression on the web, desktop, etc.
Gideros Release version
SDL based generic 2D game engine
Ze Text Adventure game Builder : Create as you play !
Orx: Data-Driven Game Engine
Lumina is a visual game creation environment for building 3D games.
JavaScript framework to build game engines, games, emulators and apps
FreeCS is a free-software reimplementation of Counter-Strike 1.5.
The imaginary eight-bit machine
Modern 3D engine and IDE written using C# and C++.
A real-time game development platform
A complete web framework to create online Fighting Fantasy adventures
Portable game engine with main focus on point-and-click adventures
Generate ready-to-use disc images for your Sega Dreamcast system!
IRB is a game creation toolkit
2D game engine for traditional platform games
Open Game Bootstrap