A minimalist and cross platform System Shock source port
486 lines of C++: old-school FPS in a weekend
UI Kit for the Phaser game engine
Build Cross-platform Applications
MMORPG
scriptable game engine with built-in support for 2D graphics and sound
Game engine allows you to create own MMORPG
3D .NET engine for Windows, Linux, Mac
Rich HTML UI engine for UE4
A game engine written in the D programming language
A Flash Molehill (Stage3D) GPU accelerated 2D game engine
a very lightweight advanced terrain-rendering and 3D map rendering sys
Free-roaming 3D racing game featuring advanced terrain rendering
Plugin based multi-purpose dev tool.
Cross-platform C framework very compact libraries and tools.
Performance enhancement API for RPG Maker XP, VX, VXA.
The Flixel Power Tools are a set of plug-ins for Flixel 2.5+
Graph editing tool
C-Lesh is a game programming language for 2D games.