Plot
The game begins in 2401 when the space marine, Sergeant Cortez, is leaving the space station that he destroyed at the end of TimeSplitters 2. His ship crash-lands on the future Earth, and two fellow marines greet him. Sergeant Cortez follows his squad of marines through the valley and battles unknown masked figures and TimeSplitters. After arriving at HQ, Cortez is tasked with following signatures in the past that were created by time travel and thought to be caused by the TimeSplitters. He goes on a mission to go back in time to find a way to stop the TimeSplitters race from being created, with the help of Anya, The General's Chief Science Officer.
Using his Temporal Uplink, a device connected to the Time Machine, both of which Anya has invented, Cortez travels to the small Scottish island of Urnsay in the year 1924. There, he meets a man named Captain Ash, who seeks Cortez's help. After raiding a castle with Captain Ash, Cortez confronts an unknown man with a high concentration of Time Crystals, who then escapes with his own time machine. Cortez then travels to 1969 to stop Khallos (whom Cortez thinks is the time traveler) with the help of hippie secret agent Harry Tipper, to rescue his girlfriend, Kitten Celeste. After defeating Khallos, Anya reveals to Cortez through the walkie-talkie on his Temporal Uplink that a mansion in Connecticut had burned down in the 1990s, leaving behind residue of Time Crystal energy.
In 1994, he is greeted by a teenager named Jo-Beth Casey, who was tasked with photographing the mansion's zombies by her friends. She tells Cortez that the house is haunted, and the two battle zombies and ghosts inside the abandoned mansion. After discovering that the creator of the TimeSplitters is a mad scientist named Dr. Jacob Crow, Cortez embarks on a new mission to foil the scientist's plans by destroying his labs throughout all of the time periods that Crow had visited. After an abrupt farewell to Casey, Cortez travels to 2052, where Crow has advanced his gene-splitting experiments. Cortez meets Amy Chen, a highly trained spy sent to defeat Crow as well. They both fight through his lab facility to find Crow, who escapes again.
Cortez travels to the year 2243, where machines now rule the planet, and have waged war on humans and each other. Cortez hacks into one of the machines, identified as R-110, and allies with him. He also teams up with a small group of cyborg rebels fighting against the machines to make his way to Crow's now-extremely large and powerful lab, filled with thousands of TimeSplitter embryos. Cortez manages to destroy what he can of the lab, but is not strong enough to defeat Crow, who himself has combined with the TimeSplitter race and a war machine. Anya sends Cortez and R-110 back to 1924 to stop Crow before he can further his lab experiments in the first place.
Now in 1924 again, he and R-110 make their way to Crow. Cortez finds Dr. Crow fused with a large bipedal robot. Crow destroys Cortez's ally R-110, leaving him and Cortez face to face. Knowing he can't defeat the scientist alone, Anya sends Cortez back in time a few minutes to when he first arrived in hopes of being able to double-team Crow with two Cortezes (and R-110, who was never destroyed as a result of the time loop).
After Crow is defeated, Cortez puts a raw crystal into a device that causes a chain reaction that destroys the entire compound. Anya warps Cortez and R-110 back to HQ, leaving Crow and the Time Crystals to be destroyed. Cortez, Anya, and The General approach the window and observe the barren desert land restored to its former form; a lush, green forest filled with life. However, the Temporal Uplink on Cortez's wrist, the large time machine in the room, and R-110 all disappear due to the time paradox.
