It seems like the following [cryptic achievements][1] are only available on the Steam version, not XBLA.

- N#7*<1!23
- &*>?1$
- (=+66&1$
- ^**5%_=+12
- *|-0&&
- N&8^2^%$1``

The "description" on all of them is: 8*(@31^

  [1]: http://steamcommunity.com/stats/SuperMeatBoy/achievements