Given it's your first jam and you only had four days, this is really good! Of course, I wish there were more levels, but that's a compliment more than criticism. The thing I think most needs work is the detection for when boxes are selected by the cursor. They were a bit finnicky to click on, to the point that I couldn't solve the puzzle it was introduced for way too long. I also think Q is a bad button for a dash, since you have to take a finger off of a movement key to press it.
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Thanks for the feedback! I've had some people playtest it a while ago, and they also said the same about the cursor being a bit weird. It was because the cursor sprite I made was centered to the normal cursor, instead of at the index finger, so you kind of clicked with the back of your hand... I fixed that sort-of-bug some time ago, though I unfortunately cannot reupload the game due to the game jam still being active. I also changed from scaling the block, to giving it a green overlay, to avoid mixels. I myself most of the time use the arrow keys for movement, so I didn't really think of Q being a bit unconvenient. I shall assign the dash to shift then :D