Best free "base building" games

Base building games focuses on creating and managing a hub that grows over time. Players gather resources, construct structures, and expand their settlement while balancing efficiency and survival. Progression often follows a tech tree, unlocking new buildings and upgrades. Some games emphasize creativity in layout and design, while others stress defense, requiring fortifications and automated systems to withstand enemies or disasters. Subgenres range from strategy-driven titles like StarCraft, where bases fuel armies, to survival-oriented games like RimWorld or Factorio, where careful planning ensures survival. At its core, base building is about growth, resilience, and creative problem-solving.