Sci-Fi

Sci-Fi themed games are games that are characteristic of science fiction literature; the narrative is dependent on the impact of scientific discoveries that do not yet exist in reality. Some games, such as those in the Half-Life series and Unreal series take place in a sci-fi universe that was created specifically for the purpose of the games. Others may take place in existing sci-fi universes, such as licensed Star Wars games. Common elements of sci-fi themed games include futuristic settings, high-tech items and weapons, and alien characters.

Unreal Tournament 2003

Unreal Tournament 2003 is an online FPS from Epic Games and Infogrames, and the follow-up to the highly successful Unreal Tournament. UT2003 features improved graphics, improved physics, faster gameplay, and a higher emphasis on teamplay over its predecessor.

Shadowgrounds

A top-down third-person shooter. You are stationed on one of Jupiter's moons which was recently colonized, and are called in to investigate the cause of a power outage. Aliens threaten to overwhelm a nearby colony. Only you stand in their way.

Giants: Citizen Kabuto

Giants: Citizen Kabuto is a third person shooter from Planet Moon and Interplay. Gameplay is unusually varied, and spans three campaigns with three characters - the heavily armed, high-tech meccaryn Baz and his squadmates, the sword-wielding, spellcasting sea reaper Delphi, and the enormous, village-trampling Kabuto himself.

Serious Sam: The Second Encounter

Serious Sam: The Second Encounter is an FPS from Croteam and Gathering of Developers. You play as Sam "Serious" Stone, and do battle with thousands of alien nasties throughout various historical set-pieces, using an array of diverse and enormous weapons.

Command & Conquer: Red Alert 2

Command & Conquer: Red Alert 2 is an RTS from Westwood Studios and EA. In the alternate universe where Germany never rose to power, the Allies and Soviets are at it again, but this time the Soviets have launched a full scale invasion of the US. You can command Allied forces and repel the invasion, or command Soviet forces and lay waste to the US and its allies.

Quake III Arena

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

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

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

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 (Steam)

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...