unmissable and obvious: just beat all 100 levels

Collect all 10 paint buckets. They're on levels 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100.


Collect all 10 gems. I'm not 100% sure on this, but they seem to be on every middle level, i.e. levels 5, 15, 25, 35, 45, 55, 65, 75, 85, and 95.


Level 100. Go right to clean your color off (make sure to touch a paint blob in the hub world first). Right above that white blob is the secret room. There's also the final paint bucket in there.

If you were diligent in collecting every gem and paint bucket prior to this, then you'll get like 4 or 5 achievements in the same minute 8)


Level 75. Bottom right area.


Level 1. After collecting all 10 gems. End of level. You may have to quit the level and collect the star a second time. This achievement is a little bugged. You're justified in using SAM here if it won't unlock. In my case, it gave it to me on the second attempt.

That was easy :D