Zero-K is a free, open-source real-time strategy game for Windows, macOS, and Linux. It is based on the Spring engine and is set in a sci-fi universe where two teams battle for control of a map. In the game, players build and manage an army of units, with the goal of using their forces to outwit and outmaneuver their opponents. The game features a wide range of units and weapons, as well as customizable options that allow players to tailor the game to their own style of play. Additionally, Zero-K features an extensive map editor, so players can create their own maps and scenarios. The game offers both single-player and multiplayer options, as well as a thriving online community.
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Discontinued Dune II is suspended because Westwood shutdown here is more info: https://www.gamespot.com/articles/ea-consolidates-studios-closes-westwood/1100-2909852/