Mainframe Defenders is a tactical retrofuturistic strategy game available on Xbox One, where players lead a squad of four prototype units to protect an AI-controlled research complex from a computer virus. Players navigate through the complex, repelling assaults, destroying unit fabricators, and downloading valuable data while facing various infected nodes. The game emphasizes diverse tactics, allowing players to use strategies such as overheating enemies or employing debuffs to gain the upper hand.

The game features over 100 obtainable items that players can combine to build powerful squads, similar to deck-building mechanics in card games. With unique enemies that counter specific strategies, players must choose their targets wisely. Procedural level generation ensures that each mission presents new challenges and objectives, keeping the gameplay fresh and engaging. The retro-inspired graphics and hybrid synthwave soundtrack enhance the immersive experience.