Fun little mechanic, but the true standout here is your level design. Well done and well-tuned puzzles, which is impressive for any jam. Plus it's clear you spent time thinking out the world structure along with your lock and key progression. Out of curiosity, how much playtesting did you do to get the levels to this state?
I would've appreciated feedback that let's me know when I've got the block positioned sufficiently into the clear containers as I sometimes got frustrated thinking the controls weren't working, when actually the block was four pixels too far to the right.
Additionally, it seems that some abilities must be activated in a certain order, or they won't work. For instance, on the red block before the final switch, if I shrink it first, then try to slide, it won't work. But if I slide first, then shrink, it's fine.
Tiny note, the readability of the platform to the left needed to exit the lowermost room is poor because it's so dark. It was hard for me to understand how to exit this area.
Overall a good time, kept me engaged the whole way through. Thanks for making this!