Real Time Strategy game engine supporting early Westwood classics
Endless Sky is a sandbox-style space exploration game
Open source clone of the Age of Empires II engine
Widelands is a free, open source real-time strategy game
RTS game with the theme of Strategy by Design
Seven Kingdoms: Ancient Adversaries
Arianne is an engine to develop multiplayer online games like Stendhal
0 A.D. is a free, open-source, cross-platform real-time strategy game.
Cross-platform, GPL reimplementation of the classic : Syndicate
Real-time Strategy
Europa Universalis 4 save game editor
Online War system for IL-2 Sturmovik and Iron Front in ArmA 2
An enhanced version of 7K:AA (Seven Kingdoms: Ancient Adversaries).
A free 3d game for PC that does not limit the player. Fight,Build,Gain
Open source FPS/RTS Game
Snake Feast is a fun, addictive arcade game where you control a snake
Cross-platform real-time strategy game (3D)
RTSish Game Engine
Java RTS framework
Mech Station Beta - Tower Defense like Game
A simple gui game that plays the game bagels with users.
Open source revival of the game Transarctica / Arctic Baron
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.