System Shock 3

The sequel to System Shock 2 (BioShock is it's successor, not sequel).

Story
You are a training space marine on a large space station owned by NEXUS Space Corp. which is threatened with being attacked. Once you are trained in combat the space station experiences a large shock because of a missile attack. Because of the largeness of the station, only a small part of it is damaged, but it suffers more strikes. You are forced to fight off a group of space mercenaries who are attacking the residential district of the station. Once you have killed them you find that some of the people on the station have been mutated into strange zombie-like creatures. You then meet up with some military soldiers and scientists and are supplied with new weapons. They tell you about some mercenaries holding the Ambassador of the NEXUS corporation in his office. You then rescue him and he tells you to evacuate the ship before it is destroyed. Once you kill all of the mercenaries and mutants, you take off in an escape pod to the mercenaries' base on the planet Keirtak, their home planet. Once you make it inside, you find their secret weapon; a gigantic mutant army who are heavily armoured and armed. You are then captured and knocked out. You awake in a surgical room and undergo a gruesome procedure but are rescued by a squad of soldiers. You awake again in a room in the NEXUS base's lab but you have multiple cybernetic implants. You are then told to go back to their planet and kill the mutant army. Once you have fought through the mutants you find a mech-suit with ultimately destructive weapons. You then find the station where Maz' Ohklarr, the large, alien overlord who leads the mercenaries using strange psychic powers is hiding. You then fight him with the help of other soldiers in mech suits. Once they are killed you finish off Maz' Ohklarr and are killed by a large nuclear explosion.