7. Sniper Elite
While the Sniper Elite series, though maintaining its original appeal, eventually rounded out to a more generic third person shooter game as it went on, the original had none of the many safety nets the sequels would add in.
It was you a sniper rifle, and a list of targets. You have a certain amount of bullets, and no backup. Eliminate your targets without getting caught, or you die. Simple as that.
Oh, and since this is WWII, your gun makes just as much - if not more noise - than your average gun, so make sure you have a good hiding spot and that you make every shot count. Because there's always the risk that taking out even one guy kicks the entire hornets nest.
Sniper Elite makes you take account of a lot of different factors before you even shoot one bullet, making for a nerve wracking, palm sweating experience that at least has the common courtesy of rewarding you with those dazzling x-ray bullet effects the series is most famous for when you get off a perfect shot.