If you're not familiar with the Metal Gear Solid series, well this is a wonderful place to start (this is the game that details the beginnings of MGS's notoriously complicated and interwoven storyline.)
Consider renting MGS 1, MGS 2, MGS 4 after this one. You'll be hooked! The premise of the game is summarized as "tactical espionage action" (it's right on the game title too). You are black ops soldier (codenamed) Naked Snake, trained by the legendary "Boss." You are sent into cold-war era Russia to (eventually) save the world from the evils of the power-hungry Volgin & his secret weapon; Metal Gear.
Enough on the story- the best part about Metal Gear games is the tactical action! You have so many different choices when trying to accomplish an objective. You can: A) Kill all opposing forces- quietly; B) Kill all opposing forces- (with the loudest, biggest guns, grenades, c-4 etc) C) Use non-lethal force (choke-hold, tranquilizer darts, knock-out). Different actions like pointing a gun at an enemy's back will make them surrender their weapon! The enemy AI is smart though so be careful!
--Option C will usually get you killed or overwhelmed by enemy soldiers. You learn, stealth & omitting conflict is often the answer to progress-- Throughout the game you will have to rely on hiding, either by hanging from railings, in lockers, under things, or blending into the environment via selecting suitable camo- it feels great to sneak up on an enemy!
This is the updated version of Metal Gear Solid 3: Snake Eater, featuring some wonderful additions; notably! you can now switch out of the fixed camera angle and use the right control stick to move the camera. This simple fix over the original makes a world of difference- so far (I have yet to play MGS4) this is the only game in the MGS series that has a controllable camera.
I have to emphasize this because it just makes the game more fun- you can peak around corners better, see enemies coming, and act accordingly.