anyway, why not make a puzzle challenge? like one of those point-and-click flash games you every now and then (except in 3D space and in Blockland and built around the acknowledgement that it'll be played by many people at once)that'd be pretty cool, and i'm sure it'd get a few plays.
pirate RPG with a shop and classes
Think of a gamemode that no one has not made yet, or hasn't been hosting in a long time.