Competently made game with a strong focus on its main mechanic. Restriction on colour selection together with changing starting colour keeps different levels distinct and allows for learning the colour mechanics one-by-one.
Non-pixelated GUI font clashes a bit with the rest of the game's look. Pixel art is fully usable, although could use some more practice. Box folds are the most apparent example. However,I love the colourful guidebook in the bottom right.
While having access to the full guidebook from the start is informative, it can easily overload a new player. Restricting the information to colours available in the current level might be preferable.
Music loop is very short, although it didn't really get repetitive quickly for me. Good choice for the Jam.
Appendix - bugs
You are able to block the Garbage Shapes with the yet-to-be-dropped shape. You are able to bounce the garbage Shapes outside the box and, if you balance them on the edge, they will persist, like a fancy spectator to your gameplay. If you throw them out of the box, you'll lose a life.
The Yellow Shape information is inconsistent with the gameplay. Yellow Shapes turn Garbage Shapes into Yellow Shapes. I was not able to get the second sentence of the guidebook to play out.
