What do you mean "can't choose enemies"? I'd be one of those pipe plants and mess people up by moving irregularly :P Honestly, a Mario MMO would only be fun IMO if one could control any character. The core mechanic could be that everyone starts as a ghost that then can possess any character in the world, and then do quests that require that character. Characters that aren't possessed keep to their scripted paths and tasks, and dying equals falling out of the possessed character. Heroes like Mario would be sought after like crazy, which would make their quests the hardest to complete since a lot of people--if not everyone--would be knock their ghost out. It would drive Luigi insane! The quests aren't long though, more like a short level in a classic Mario game, and characters would be restricted to certain areas so that someone doesn't wonder off with a [i]piece of the puzzle[/i]. It would be like tons of [i]Oddball speedrun[/i] levels in an open world.