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