The "start the game" achievement in The Simpsons Game. But seriously... I think the TF2 achievements are too easy, I mean... "Set 5 persons on fire" All of the achievements are easy on custom-made maps. And seriously, the achievements that are based on defending something for so so long or winning in 5 minutes... they can be done with no one else playing the same map as you! "Win hydro in 5 minutes" I won in 1, because there was no one else there... "Achievement unlocked!"