Quantum Theory (クウォンタム セオリー, Kuu~ontamu seorī) is a third-person shooter video game for the PlayStation 3 and Xbox 360. It is developed by Team Tachyon and published by Koei Tecmo Games. The game was released in September 2010. The game centers on two characters named Syd and Filena who must fight through a "living tower". The game features a cover system that constantly adds and removes cover. Gameplay The game is a third-person shooter incorporating a cover system. Players can fire their weapon from the hip, aim down the weapon sight for precision, or blindfire from cover. Enemies explode upon death and a successful headshot is rewarded by a slow motion close up view of the head exploding. Syd can throw Filena as a projectile weapon. Syd can use his guns as melee weapons. Syd's initial melee attack can also result in a follow up attack by Filena. Some levels feature environments that can change dynamically, including moving platforms that Syd must hang on to or jump off. Bosses make appearances throughout the campaign, requiring the player to identify and target their weak points. Plot Setting Set in an organic sci-fi world, years have passed since a world war left the world in a catastrophic state, leaving only a few survivors. In a new community "Cocoon", life has been threatened by a black material called Erosion, creating a post-apocalyptic environment. Surviving humans form a militia to conquer the Erosion and set out to take down the "Living Tower". The main character, Syd, intends to destroy the Tower. He meets Filena along the way, as they both ascend to the top in their search for answers. The tower is constantly eroding, and intensifies as the game progresses. Story Most of the story takes place within the tower, beginning with Syd and a woman named Nyx trying to escape the tower as it begins to fall apart. As they continue to fight their way out, Nyx suddenly collapses, dying. Syd reveals that because she is part of the tower, she will die with it. Syd leaves Nyx behind telling her to "die well". Syd then escapes the tower through unknown means. The story then flashes forward to where Syd and other soldiers fight through destroyed city streets against the Diablosis as they make their way into the "living tower". A poisonous growth called "the erosion" lives there, and their mission is to