Nice little puzzle game!
Plays pretty well and the fluid simulation is awesome and it fits the theme quite well. You build a platform or you destroy it. It's simple, easy to learn and some of the later levels took more than one try which is nice and was not annoying at all because the levels are super short and not dragged out.
The visuals are simple but also pleasing. It gave me a more colorful Game Boy vibe. I like the minimalism. Not a lot of stuff is going on and the focus is on the sand and platforms which are super easy to distinguish from the rest of the levels.
In the beginning I had a bit of trouble to get what the game wants from me. In level 3, I think, the one were you climb the first cliff, I really thought the game wants to teach me how to reset the game. There was no character, only "R to restart" was written at the top of the screen. I think it would be totally fine to not lock the character out of screen until you build a bridge and let the player instead control the character. It would feel more natural.
I didn't have problems with the controls but I would adding space as additional jump key would be really nice.
It was short, entertaining and fun to play. Very good jam entry. Great job!