Tower defense game where you stop waves of aliens from stealing power cores by placing weapons along fixed paths. You've got 21 maps with shifting terrain that changes mid-wave, forcing you to adapt your turret layouts on the fly. Campaign mode follows a story with voice-acted characters. Beyond that, you can tackle hundreds of challenge variations on those same maps—different enemy types, restricted tower choices, survival modes. Multiplayer lets you compete head-to-head or team up in co-op. There's also a level editor that connects to Steam Workshop, so you can build custom maps and download what others have made. Turret variety and resource management drive the strategy—you're constantly deciding whether to upgrade existing towers or expand your coverage.
