Well for the last week I've been playing Call of Duty. It's a World War II first person shoot 'em sort of game. Quite realistic engine - although not as realistic as HalfLife 2. It's rather gripping.
You play the game through the eyes of three different soliders (fighting in different bits of the war), these being Private Martin (American dude), Sergeant Evans (British dude) and Alexi (Russian dude). What makes the game stand out to me is that you play the whole thing as a team. There's no running in and doing the whole thing alone like there is in lots of other games. It's a team effort - that said lots of my team used to die!
Another part of the realism factor is the lack of weapons you can hold. You can hold 4 - one of which always being a pistol, and the other grenades. Oh, and there's no health packs to get you through the levels either!
It tries to reenact famous parts of the war - such as the retaking of Stalingrad and the final mission being to help raise the Red Flag above the Reichstag. Playing the game went someway to show the human loses of the war. When the red flag was raised and the closing cut sequence started to play, a tear appeared in my eye! But then that doesn't take much, I suppose!
To put it bluntly: a great game!