Mindustry

Mindustry is a free, open source hybrid of factory automation and tower defense. Players mine resources, design production chains to convert ore into materials and ammo, and use the output to build defensive turrets that hold off increasingly difficult waves of enemies. The game blends the base-building and logistics of Factorio with the wave-based combat of tower defense games like Dungeon Defenders.

The game includes a built-in map editor, a custom logic processor for advanced automation (programmable in a simple scripting language), support for both solo and team-based multiplayer, and cross-platform play across Windows, macOS, Linux, and Android. The 8-player co-op mode is a particular highlight — teams build interconnected supply lines, share resources, and coordinate defenses against massive late-game attacks.

Mindustry has no single commercial counterpart — it occupies a niche that is partially covered by Factorio, They Are Billions, and Dungeon Defenders — but the open source release and the 28k+ community on GitHub make it one of the most active indie RTS projects available today.