Captain Nathaniel "Nate" Renko, is the silent protagonist and part of an elite Special Forces recon squad sent to investigate bizarre radiation emissions coming from a mysterious island known as Katorga-12, only to crash land there. He has to rally up with his squad (what remains of it), while escaping monsters and Russian soldiers. He goes back in time to the year 1955 where he must set things right. He finds himself in the company of Kathryn, a Mir-12 agent who helps him throughout his mission.
- In Singularity, there's a camera that can be used to take a picture of Renko, along with a mutant behind him. The flash makes him cover his face, though.
- Even if the player shoots past Renko in the knee or other non-lethal areas Renko will still die.
- During the game you find various strange writings on the walls. In the end game is revealed that Renko himself left them to warn his past self.
- Some of those writings warn about Barisov (probably referring to the good ending when Barisov gains the TMD and unites the world under the Soviet Union).
- (Time Paradox) When you have to kill yourself in the past, it results in a time paradox, as if you killed Renko in the past then how were you able to travel from the future to kill your past self?
- It is possible the man seen at the beginning of the game could be an alternate version of Renko who did not pull the trigger, there by causing the current Renko to repeat everything all over.
- It is also possible that after you kill your past self, you are reborn in the current time controlled by the Soviet Union. Because it is the past before Renko was actually born. But this is just a possible explanation to the Time Paradox.
- It is further possible if the 'infinite parallel timeline' theory is considered.