Here is the full list of all 12 Ms. Splosion Man achievements.
Find Star Road.
Find a secret exit.
Download and play against a Ghost from a Leaderboard entry.
Destroy 10 pieces of scenery.
Complete Single Player level 3-14 without touching the ground.
Complete Multiplayer level 2-14 without one of the players 'sploding.
Complete all of the Single Player levels.
Complete all of the Multiplayer levels.
Complete all of the Single Player levels in Hardcore Mode.
Collect all 47 pairs of shoes in Single Player mode.
Collect all 50 pairs of shoes in Multiplayer mode.
Buy all of the unlockables.