Neat but missed game: Costume Party

Not my own game (hey, where's the screaming guy telling me not to advertise my own gone?) but according to its highscore table it hasn't gotten much attention yet:

Costume Party (http://hamumu.com/game.php?game=FREECOST)

Fairly basic platformer with simple graphics, but the big bonus is the online creation and level sharing, plus the Costume system. Basically, the player character can switch between 5-8 different characters who all have almost completely different rules. You can make levels specific to one character, or switch between them in the middle, or even have several at once. It's a bit like OmniLudiCon on acid.