Sci-Fi

Quake 3 is an online FPS from Id Software and Activision. In a departure from its predecessors, it completely lacks a traditional singleplayer campaign, and the emphasis is mostly on deathmatch.

Half-Life 2 is an FPS from Valve Software, and was one of the most highly anticipated sequels of all time. You return as Gordon Freeman, the strong and silent-type physicist, and you must do battle with an alien race of enslavers to liberate the surviving remainder of humanity on earth.
Also applies to Half-Life 2 Lost Coast free downloadable level.

Unreal Tournament is an online FPS from Epic Games and GT Software. Its main competition being Quake 3, it distinguishes itself from the Quake games by focusing on team-based games such as team deathmatch, capture the flag, and assault, rather than free-for-all deathmatch.

Deus Ex is an FPS/RPG hybrid from Ion Storm and Eidos Interactive. It is most notable for its free-form skill-based gameplay, which allows nearly unlimited solutions to missions, often allows for multiple outcomes, and lets you shape your character to be best suited for your style of play by allowing you to develop the skills of your choice.

Half-Life is the groundbreaking FPS that follows the "everyman" hero Gordon Freeman. This is the first installment of the ongoing series, which ties together aliens and government conspiracies. Really, this game doesn't need any introduction...

The Chronicles of Riddick: Escape from Butcher Bay is an FPS from Starbreeze Studios and Vivendi Universal. The plot serves as a prequel to the 2000 film Pitch Black, and features Vin Diesel's voice and likeness.

Project Eden is a hybrid between first- and third-person shooter with an emphasis on teamwork and puzzle solving over combat. Players switch between control of four UPA (Urban Protection Agency) agents, each with their own special abilities, as they work their way through a city that has grown upward and upward, leaving delving buildings and neighborhoods "below city limits.".

RF Online, originally named 'Rising Force', is a 3D MMORPG developed by CCR. The first version of the game was released in South Korea and was later followed by Chinese (Mandarin), Japanese, Portuguese and English translations. The North American/European version of the game launched its retail phase on February 21, 2006 and closed on November 10, 2008. RFO is currently a free to play game.

Star Wars Jedi Knight: Dark Forces II (abbreviated to Jedi Knight and Dark Forces II) is a first person shooter computer game. It was developed and published by LucasArts and released on October 9, 1997. The storyline in Jedi Knight follows Kyle Katarn, the protagonist of Dark Forces. Katarn's father has been murdered by a Dark Jedi over the location of The Valley of the Jedi. Katarn follows the Dark Jedi to the valley to confront his father's killers.