No missable achievements (plus 6 unknown)
Sign in with Steam or Xbox to track your progress, and:
Complete a level with Ghosts on it without trapping any Ghosts
Be struck by a Fireball while encased in ice.
Complete level 21, the Lode Runner man.
Build a mod with 5 valid levels.
Complete a level with 3 ghosts in it.
Play through 5 levels of a custom mod.