System shock 2

The much-improved sequel to the game System Shock, which continues the story 42 years later and pretty much improves on every aspect of the game while keeping the concept of merging
role-playing and first-person shooter genres in a near-seamless and highly-addicting way. It won several game-of-the-year awards and probably would have won many more had Half-Life not been released in the same year. If you have not played this game, you are missing a treat. It has a HUGE cult following. It is the most immersive game I have ever played.