Super ambitious for a jam game. I appreciate how the later levels mixed things up by blocking off spaces with mushrooms. That being said, it's pretty easy for the player to snowball out of control and the game can't do much except feebly send demons while the player is forced to watch them slowly marching to the their deaths, until a new level starts and the demons briefly have a chance to fight back. More things to spend power on would probably help, since the cooldown on building towers and lack of space is the bottleneck. Towers having upgrades seems like the obvious way to expand the game.
Still, it's a jam game, and what's there is plenty for 3 days. Also, Hecatia. <3