Alienation is an action role-playing shooter video game developed by Housemarque and published by Sony Interactive Entertainment for the PlayStation 4. It was released in April 2016 worldwide. The game is an isometric twin-stick shooter in which one to four players defend themselves against an alien invasion on Earth through increasingly-difficult levels. Players can choose one of three character classes, each with its own abilities. Players can upgrade their weapons with collectables, known as upgrade cores. The development of Alienation was hinted at in early January 2014 and announced at the 2014 Sony Gamescom convention. In 2015, the developers released details of the gameplay and classes and its first trailer. According to Sony, the game would be released sometime in 2015; it was delayed until March 2, 2016. After another three-week delay, it was released as part of a Sony promotion releasing six games in seven weeks. Since the release of Alienation, Housemarque has updated the game with free and paid expansions. It received generally positive reviews, with praise for the twin-stick elements and cooperative multiplayer feature. Reviewers criticized the lack of a local co-op mode, which was later added, as well as the game's lack of variety in regard to weapons and ammunition. Gameplay and plot Alienation is an isometric twin-stick shooter game set in a future in which aliens are invading Earth. After a large portion of the population has been murdered or mutated, humanity's fate rests with a group of four soldiers from UNX (a military group assembled to help prevent alien attacks). The game features a single-player mode, a local co-op mode, and a multiplayer mode that allows four people to play at once, with each player controlling a heavily-modified soldier from one of three character classes: Bio-Specialist, Saboteur, and Tank. Each class has its own weapons, movement mechanics, and abilities, and can be "leveled up" to level thirty. The Bio-Specialist can heal other team members and create poisonous trails. The Tank is able to create a shield behind which players can stand and can "blow everything away", allowing players to maneuver more easily. The Saboteur has the ability to become invisible, and can call in airstrikes when needed. Players defend themselves against hordes of aliens through increasingly-difficult levels. In multiplayer mode, players can revive each other and use checkpoints in the levels to respawn if they die. Players can find new weapons in random drops.