Sniper Elite...in fact, it doesn't have its own CD Key, so you can get it from the Interwebs...and play it online...
The SP is fun as hell, and often very intense. They give you multiple ways to complete an objective, for instance.
You're supposed to kill a high-ranking SS officer who goes defector to Russia. You'll be expecting him at some big-ass park/square controlled by the NKVD. Now, you have 3 places to shoot him from. You can either distract the guards and get a position near them, or hide in a derilict building overlooking where he will arrive. You can take a back route to a wine cellar to get VERY close to where he will stop, and hide under a truck.
Or, as I did, you can dump some TNT right in front of that truck, get back to that derelict building, wait 5+ minutes (yes, 5+ minutes) and wait for him to come. Once he arrives, fire and watch the bullet debrain him, then quickly hit the TNT and blow the truck to hell, and pull out your PPSH and cut down the guards nearby, and run like hell out of there.
I personally got sick of the game...the bullet-cam headshots made me feel dirty after a while
I do, however, remember my very first time playing. I shot a NKVD dude in the chest (and watched the bullet go there), and he collapsed. His buddy just comes out and picks him up. I panic, level my sniper rifle, and fire in his general direction. Bullet cam kicks in, and I watch as the bullet takes off his testicles. Fun.
Enough rant
Get the game, or get it from the interwebs.