Clonk Rage - Real-time multiplayer game. Players can download more than 47475 maps at ccan.de
ANNO - ANNO is a city-building and economic simulation video game series, with real-time strategy elements.
Endless Sky - A space exploration and combat game similar to Escape Velocity
Stronghold - Stronghold Crusader is a RTS game from the series from Stronghold.
NAEV - Naev is a game about space exploration, trade and combat. Players travel the galaxy and earn money by trading, fighting and performing missions.
The Settlers Online - The Settlers is a free web browser based strategy game along with a gameplay that drops anywhere between Age of Empires and the online strategy style.