Half-Life 2

THE GOOD:
*Graphics (above all else - just look at the faces!)
*Enemy A.I. (grenades in hiding spots and flanking tactics will keep you on edge)
*sound fx (the strider cannon noise is massive)
*physics (rag dolls and objects with real gravity?!?!?)
*Gravity Gun!!!(Can you not have fun by cutting zombies to bits with sawblades and shooting paint cans in their faces?)
*Massive worlds (even Metroid Prime is speechless)
*controls (even a newbie can pick-up on them)

THE BAD:
*Ummm... unless you have a super-powerful CPU, the framerate will not forgive you

SUMMARY:
Okay, I was never a PC gamer up until I played this game, and had no experience with using a keyboard and mouse to fire a gun...
So I was a little unsettled to get into Half-Life 2, which ended up being one of my favorite games of all time. Anyone following the series will immediately pick up on the continuity of Gordan Freeman's fluidly-done existence. The sequel picks up where the original left off (if you chose to follow the G-man) and has the G-man dropping you off at an arriving train in City 17, a depressing slum run by Combine (a humanoid alien species) and a lying bastard named Dr. Breen.
As with any Half-Life, there are no 'real' cut-scenes to the story, always leaving you in the action and free to ignore the NPCs' dialogue (if you wish). But if you do so, you will miss one of the best storylines I ever experienced in a FPS.
The action is almost non-stop force-feeding you hordes of Combine, head crabs, zombies, airships, striders, etc. But thanks to the new weaponry you are equipped with (the Gravity Gun is the best thing evar), you can come out the other end of a tunnel smiling with the blood of your foes dripping from the barrel of your gun.
I could gush on and on about this game's greatness, but since it is a PC game, you will have to lay down a lot of cash to get the best experience.
And so I say "buy this game, you won't regret it ever!"