Splinter Cell, a Stealth Action game very much like Metal Gear Solid, except not nearly as over-the-top ridiculous awesome (although this game is pretty awesome). You play as Sam Fisher, America's resident badass to prevent major world conflict (particularly war) and save the lives of many many people. Sam is a no-nonsense guy who is VERY good at his job.
The story is pretty good, a little cheesy at times but good nonetheless. You are basically traveling across the world infiltrating places (EVEN THE CIA) in order to find out more information about your enemies. Sam is an NSA agent, part of Third Echelon, which is supposed to be super top-secret, the kind that if you are caught, it will cause an international crisis because you are probably breaking a few treaties.
Sound is a MAJOR element of the game. The effects are pretty good and whatnot, and "Name of the Game" by Crystal Method is a kickass song. I'm giving this a 10 because the game relies on you being STEALTHY, which means sneaking and timing and making minimal errors, prepare to save often!
Considering the game was released in 2003, the graphics are way ahead of its time! You use the element of surprise and hide in the shadows in order to achieve your objectives. This combined with the sound factor from above basically make you a modern day ninja with night vision and death at your fingertips.
A little complicated at times, things aren't always so obvious, and that is a really good thing. The game is really easy if you know what to expect, so on your first playthrough be prepared to have a lot of "WTF" moments. With everything flowing together so well, you really find yourself immersed and FEELING like Sam Fisher. When you have to run, your heart will race. When you have to be quiet, you will find yourself holding your breath. This game is truly magnificent for its time.
Naturally, I would give this a 10/10, but I have one major gripe. The xbox version came with FREE DLC, which were 3 additional levels after the end of the game. We don't get those on PC. Apparently there is a way to grab them, I think it was supposed to come with a 1.3 patch if you also have Chaos Theory (Splinter Cell 3) installed, I didn't try though. The game isn't any less good because of it, just a little depressing.
I should also like to note, if you are looking at the sequels, Steam doesn't have Splinter Cell 2, Pandora Tomorrow. There is apparently a PC version you can go buy or something, so I'm not sure why it isn't on Steam, it is depressing, so until we get it, enjoy playing Chaos Theory and so on.