Minetest

Factorio-like tower defense game. Build production chains to gather more resources, and build complex facilities.

Ad-less chess server powering lichess.org, with official iOS and Android client apps.

Voxel game engine (formerly Minetest). Play one of our many games, mod a game to your liking, make your own game, or play on a multiplayer server.

Minimalist text adventure game for your browser.

Transport tycoon simulation game.

The Battle for Wesnoth is an Open Source, turn-based tactical strategy game with a high fantasy theme, featuring both singleplayer and online/hotseat multiplayer combat.

Unique puzzle game designed for geeks and developers, where you solve the puzzles in the game by reading and writing Javascript.

Cross-platform real-time strategy game of ancient warfare.

Add network play functionality to Rockstar North's Grand Theft Auto game series, in which this functionality is not originally found.

Competitive top-down shooter blending Counter-Strike with Hotline Miami. Runs on Linux, Windows, MacOS and the Web.

Open Source on Springrts engine. Zero-K is a traditional real time strategy game with a focus on player creativity through terrain manipulation, physics, and a large roster of unique units - all while being balanced to support competitive play.