Singularity

During the Cold War, an island named Katagora-12 was discovered to have a supply of a mysterious element named E-99 used by the Soviet Union until a series of strange occurrences provoked the evacuation and abandonment of the island. In 2010, the US military detected a spike of unknown energy from the island and sent a team to investigate. Marine Nathaniel Renko is taken into a mysterious wave of energy; later on, he discovers that he was sent back to 1955, where he saves the life of a political scientist named Nikolai Demerchev in a fire. Returning to the present, he begins to see and realize that Demerchev ultimately ended up succeeding Stalin and took over the world. Renko barely escapes Demerchev's clutches with the help of a resistance fighter named Kathryn. Finding scientist Barisov's secret Vault, he discovers a device capable of accelerating or reversing the progression of decay in objects infused exposed to E-99 energies; during the early days of the island, E-99 was discovered to have time-altering properties, resulting in multiple experiments, equipment, and technologies as well as mutations, accidents and travesties of all varieties.

Traveling through a rift into the past, Renko saves Barisov from an assassination attempt at the hands of Demerchev's agents in '55, and the later guides him back to the rift. An elderly Barisov messages him to travel to the tower he built, and Renko fights past camouflaged, teleporting creatures nicknamed the Zek, and defeats the giant Zek king. After using electric fences to force away the rest of the hordes of mutants, Renko and Kathryn meet with Barisov, who tells Renko of the events since Demerchev rose to power, all beginning with an E-99 bomb that wiped out the east coast of North America. During the early days of his rule, Barisov developed a massive device with E-99, known as the Singularity, responsible for the time-distortion events on Katagora-12. Directing him to the trainline, Barisov has Renko journey through the underground tunnels and sewer systems to reach the trainyard, and after narrowly saving Kathryn from soldiers, Renko uses an energy amplification construct to use the TMD to restore the train. On a bridge, he fights the massive Queen Tick, the queen of mutated insectoids festering around the island. Getting on the other side of the island, Renko finds the ship docks, reaching and using an amplifier to restore a ship called the Pearl, where an E-99 bomb was located. After restoring the Pearl and escaping with the bomb, he is rescued by Barisov, saving the weakened Renko. The next morning, he reveals that Kathryn sacrificed herself to draw the attention of Demerchev's men to allow Renko to retrieve the bomb. Heading to a massive destroyed E-99 processing facility, he travels into a rift to the past to recharge the bomb just before the facility's original destruction.

Barisov and Renko head toward the Singularity as the storm becomes worse, causing Renko to face scores of old and modern soldiers as well as swarms of mutants. Reaching the Singularity, Renko goes into the past and destroys it with the bomb but returns to discover that Demerchev simply rebuilt it in that time. Realizing that keeping Demerchev from being made leader is the key to rewriting history, Barisov urgers Renko to go back to the day of the fire to stop himself from saving Demerchev; Demerchev, however, reveals that Renko already attempted it before in a previous loop of events. If Renko kills Barisov, he unites with Demerchev, but they eventually splinter in their control of the world, resulting in civil war. If Renko kills Demerchev and Barisov, he leaves to create a new world with the TMD. If he kills Demerchev and goes into the past, Renko secures the timeline by killing his past self and stopping Demerchev's rescue. Once that happens, Renko's patrol passes by a scan of Russia, with hints of Barisov's quest for world dominion.