Rememoried

Story-related and cannot be missed. This achievement unlocks after completing level 9 and picks up from the "Déja vu" achievement solution.

Level 6

Just like level 1, spin around until you see the white post, and follow the arrow. This time it'll lead you to a couch. Touch the couch to end the level.

Level 7

You'll be in a cube of stars that makes you float. You need to use these star cubes to float up higher and higher. Rememorize them as needed to keep ascending to eventually reach the house up top. Once you get high enough and close enough, the level automatically ends.

Level 8

When you start the level, you'll be looking at some dark structures illuminated by a glowing moon behind them. Note the chess piece sitting on a structure. Turn around to see another glowing moon. The goal is to walk toward this moon until you find the same chess piece, but on this side it'll have a white mask on it. You'll have to walk a decent amount, and it can be a little tough to spot at first, but keep on the lookout for that glowing white mask. The chess piece itself is relatively small. Once you find it, touch it to finish the level.

Level 9

Spin around until you see a white light/ghostly being. Chase after it and you should easily catch it quickly. This ends the level.