Non-linear hand crafted levels full of interactivity, choose your path, break stuff, play with lights, find secrets...Over 15 different weapons, including classic human weapons like a shotgun, Mac-10, rocket launcher and lightning gun as well as crazier alien weapons such as the Swarm Shooter shooting homing bees, the Spore Launcher which can lauch sentient bombs or the Belittling Eye...Over 10 enemies species, including zombies, alien soldiers and insects and more with a variety of behaviours, such as taking cover, flying, dodging, walking on walls, smelling you... The difficulty determines the number of enemies, objectives and the abilities the AI will use. The game plays noticeably different between easiest and hardest