It's war, and this time it's too close to home. The Martian mission may be over, but the aliens haven't finished playing space invaders yet. Extraterrestrial eyes have turned to a new target: they want Earth, and you're the one that has to say 'no'. Welcome to the future of Tower Defense. Sentinel 2: Earth Defense expands upon the acclaimed gameplay of Sentinel: Mars Defense. The action takes place across varied, lushly rendered Earth environments, and the alien assault force has grown more vicious than ever. Luckily, human turret technology has also advanced, and the ship weapons system provides a spectacular new way to eradicate invaders! New features: * Unleash the Sentinel's incredible ship weapons system - if you've got the power to do so... * Deploy mobile attack drones to harass the enemy and augment static defenses. * Construct boosters to buff your offense, and upgrade to top-tier towers for devastating special moves! * Pit yourself against previously unseen members of the star spawned horde. * Mission mode provides quick tactical challenges. Beat a scenario to earn achievements! * Full online high scores, achievements, friends and chat using OpenFeintOpenFeint. * Exclusive new music written by Specimen A. Classic Sentinel features: * Specialised structures and units provide unique tactical gameplay. * Use the landscape and destructible defenses to maximize the effectiveness of your weapons. * Resource harvesting and interest system adds a new dimension of risk and reward. * Assault mode provides hours of play; endurance mode is an endless challenge. * Visually stunning environments, towers and enemies with fluid zooming and scrolling. Source: The Developer Website.