Aliens Infestation is a 2D sidescroller action game co-developed by WayForward Technologies and Gearbox Software, and published by SEGA for the Nintendo DS. The gameplay of Aliens Infestation is comparable to the Metroid and Castlevania video games, where players are encouraged to search and backtrack for weapons, upgrades, and keys. The player controls one of a party of four marines and explores the U.S.S. Sulaco as well as LV-426 and Phobos in order to investigate the Union of Progressive Peoples (UPP) and Weyland-Yutani's involvement in Xenomorph development. If a marine falls in battle, another in the party will take their place.