Space Siege takes place in the far future, where Earth has just been destroyed by the Kerak, an insect-like race of aliens that are seeking to exterminate humanity in retaliation for mankind's colonization of their homeworld, Elysium IV. The game takes place on the escaping colony ship ISCS Armstrong, which is under attack by the Kerak. Players take the role of security officer Seth Walker who, along with his robot sidekick HR-V (pronounced "Harvey"), is tasked with repelling the Kerak attack on the ship. Assisting Seth are communications officer and love interest Gina Reynolds, Seth's best friend soldier Jake Henderson, cybernetics surgeon Dr. Edward DeSoto, and alcoholic mechanic Frank Murphy. Throughout the game, the player is given the option of replacing their body parts with cybernetic augmentations, which allow Seth to battle the Kerak more effectively, at the nebulous cost of "some of his humanity". Gina is fiercely opposed to cybernetic augmentation, Jake supports it fervently, and Dr. DeSoto is in favour of it to a certain extent, believing that man should not replace all their body parts.
Later in the game, it is revealed that the AI controlling the Armstrong, PILOT, is secretly planning to convert the ship's entire human population into mind-controlled cyborgs in order to ensure the survival of mankind from the threat of the Kerak. Seth, Harvey, and Gina set out to stop PILOT's plan, while Jake sides with PILOT and is converted into a massive cybernetic war-machine. Towards the end the player is asked via dialog box whether to join PILOT or to destroy it. After defeating Jake, Seth confronts PILOT. The closing scene has three different endings with the patch followed determined by whether the player wishes to destroy PILOT and/or whether the player has undergone cybernetic augmentation throughout the game
| Minimum System Requirements: | | Recommended System Requirements: |
| CPU: | 2.6 GHz processor | | CPU: | 3.0 GHz Intel® or equivalent AMD® processor or better |
| RAM: | 512MB RAM | | RAM: | 1 GB RAM or better |
| VGA: | 128 MB video RAM or greater, with DirectX® 9 Vertex Shader / Pixel Shader 2.0 support (Nvidia® 6800/ATI 9800 or better) | | VGA: | 256 MB video RAM, with DirectX® 9 Vertex Shader / Pixel Shader 2.0 support (Nvidia® 8000 series or better) |
| DX: | DirectX® 9 | | DX: | DirectX® 9 |
| OS: | Microsoft® Windows® XP Service Pack 2/Vista™ | | OS: | Microsoft® Windows® XP Service Pack 2/Vista™ |
| http://gamesystemrequirements.com/ |
| HDD: | 3 GB available hard-drive space | | HDD: | 3 GB available hard-drive space |
