Endless Sky is a sandbox-style space exploration game
Real Time Strategy game engine supporting early Westwood classics
Europa Universalis 4 save game editor
RTS game with the theme of Strategy by Design
Seven Kingdoms: Ancient Adversaries
Arianne is an engine to develop multiplayer online games like Stendhal
A 2D Real Time Strategy space combat game.
Cross-platform, GPL reimplementation of the classic : Syndicate
Cross-platform real-time strategy game (3D)
Open source FPS/RTS Game
Real-time Strategy
A free 3d game for PC that does not limit the player. Fight,Build,Gain
A simple gui game that plays the game bagels with users.
0 A.D. is a free, open-source, cross-platform real-time strategy game.
Open source revival of the game Transarctica / Arctic Baron
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
RTSish Game Engine
A suite of tools to make operating a Empire server easier
An approach where computer solves problems like a human brain does;
WeComeInPeace is a simple RTS game that aims towards multiplayer