Mindustry is described as 'Create elaborate supply chains of conveyor belts to feed ammo into your turrets, produce materials to use for building, and defend your structures from waves of enemies. Play with your friends in cross-platform multiplayer co-op games, or challenge them in team-based PvP matches' and is a factory building game in the games category. There are eight games similar to Mindustry for a variety of platforms, including Windows, Linux, Online / Web-based, Android and Mac. The best alternative is Factorio. It's not free, so if you're looking for a free alternative, you could try shapez.io or Bleentoro. Other Mindustry like games are Satisfactory, Dyson Sphere Program, Factory idle and Automation Empire.
Mindustry is mainly a Factory Building Game but alternatives to it may also be Sandbox Games. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Mindustry.