Fantastic aesthetics and good UI! I appreciate the predictor line being drawn on screen.
The concept is also really cool, but I think it would work even better if it was more fast-paced by limiting the time you have to place a block. Also, sometimes not being able to place a block because of level geometry was a little annoying. The variation in block types is pretty cool, though.
Probably could use some sort of difficulty scaling or something if you continue working on this after the jam, but pretty neat for what it is right now.