No missable achievements (plus 10 unknown)
Sign in with Steam or Xbox to track your progress, and:
Beat a REAL level without dying once (1-1 doesn't count!).
Beat a REAL level without using the checkpoint (1-1 doesn't count!).
Unlock the path to space.
Beat the game. You'll know it when you see it.
Collect 4000 Golden Diamonds, unnecessarily.