In Alien Syndrome, players take control of the game's strong and enigmatic heroine – Earth Command Trooper Aileen Harding – and battle a variety of fearsome aliens and colossal bosses. Gamers choose from a wide selection of character specialties and skills as they progress through an engrossing campaign, protected by many different types of armor and using a variety of melee and ranged weaponry. Players can improve their heroine's statistics and discover a huge number of powerful new abilities as they fight through infested spaceships and bizarre alien planets. Alien Syndrome features two fast-paced action-RPG modes – the dramatic and engaging single-player campaign, plus an infinitely replayable co-op multiplayer mode for up to four players. Derived from the classic SEGA arcade game, Alien Syndrome's new action-RPG gameplay makes it easy to pick up and play, while its depth and wealth of features and missions keeps it challenging for all gamers. Alien Syndrome features 20 different weapons including flamethrowers, quad-barreled lasers, nanobot swarms that dissolve enemies, and incendiary grenades that shoot fire geysers from the ground. Each weapon offers advantages and disadvantages, dependent upon how it is used and the specializations players have chosen to adopt. Alien Syndrome's fast-paced combat also allows for any number of combat strategies to defeat over 100 different alien enemies at one time.