The biggest installment of the award winning Sentinel sci-fi tower defense series now on PC!Take the fight to the alien homeworld and unleash a massive arsenal of weaponry. Get up close and personal on the battlefield in your power armor to execute devastating attacks and support your defenses! * An epic campaign across 20 levels.* A powerful commander unit which can level up and gain new abilities as you play.* Over 20 unlockable turrets, orbital ship weapons, automated drones and abilities at your disposal.* Customize your weapon loadout in the Armory to match the demands of the mission.* NEW: Includes new content featuring new commander, enemies, campaign, weapons and more!* Endless modes for all maps.* NEW: Steam Achievements* Classic mode allows you to compete for scores in a pure skill-based game mode. * Exclusive music by Specimen A.