Saboteur just got a steam release actually, I went back and replayed it. I really liked that the progression system was based on challenges, if you wanted to you could go and do all of them before you even started the story. It still holds up graphically thanks to the way they did the colour.

My one would be Quake Wars (2007). It was the first asymmetric multiplayer game I ever played and it was the last proper Quake game.