Neat game and I can see how it fits the theme! A lot of people already mentioned the bugs so I won't. :P
Some more feedback in the creation menu would make it more fun to use, like showing what block on the grid you're hovering over, some sound effects or particles when you select or place a piece, maybe tooltips that say what each piece does (though currently it's mostly obvious).
I appreciate how you can just press play and immediately start playing the level you set up. This has a lot of potential if you decide to keep going!
Congratulations on completing your first game jam!