This game is well done. I like the unique artstyle but the pixel character doesn't really match everything else. The lack of music might just be cause you didn't have time but I actually kind of like the feeling of emptiness and aloness that it creates. I've got a few critiques that might help improve your game.
- Shooting with the arrow keys is incredibly awkward and hard to aim. Just make it where you point and click to where you want it to go
-It's hard to judge the players position with the isometric camera angle. Fixing that is really up to you and how you want to go about that.
-The boxes are really hard to move precisely. This goes back to the last point.
-puzzles (as far as I got) Never really evolved past: push a box onto a button. A little more of a mix of variety and complexity would help
-The footstep SFX is a bit jarring. just needs some tuning.
Hope that helps. Good work getting as much done as you did for the jam I'm really impressed! All your game needs is a bit a fine tuning to take it to the next level.