System Shock 2 is truly a masterpiece; few games give you this level of challenge and depth, fun and immersion.
First off, let me just say that the tutorial in the game is the best I've ever encountered. It's fun, it makes sense, it's actually cool.....and you can skip it. There is basic and advanced training, and in each room you come across 3 other rooms, each offering training in a different area. The room is a simulation, and thus everything turns into a grid like area, not sure how to explain it, looks something like out of The Matrix. As I mentioned you can skip the tutorial anytime and make your way to another room, where you choose your specialised area.
The User Interface is very nice, you can switch between two different modes, Use and Shoot mode. In Use mode the inventory comes up as well as every other piece of information on your system and you can change weapons, change ammo type, wear armour, research unknown items, view your mission, check the map, listen to logs found on the spaceship etc. In Shoot mode, it's basically how you play most of the game, moving around and shooting, though don't let this sentence make you think this is a run'n'gun game. You can try playing it like that though, if you wish...
Researching is one of my favourite things in the game. You will come across objects which are unknown to you, and if you have invested cyber modules (think of them like 'points' in a Dungeons and Dragons game to increase strength, wisdom, intelligence etc) in this area, you can research bodyparts and other items to learn about your foes and be able to gain an advantage over them (say, a 25% attack advantage). Normally you'll need to find chemicals to finish your research, and these can be found in a chemical storage in each level (floor level on the spaceship).
Graphics are dated, but they do the job. Not much to say here, though the atmosphere is brilliant.
And now, probably the most immersive aspect of the game - sound. Very creepy, sends a chill up your spine. One time during the game which everyone will encounter stands out the most. I won't even mention anything, but once you get there you'll understand what I mean.
This is truly a masterpiece, and I can't really seem to fault the game. It's just so damn good. I wouldn't hesitate to go out and buy it if I were you, it's also very cheap now.
What are you waiting for? Go out and buy the game!