The concept is quite cool! I think it wasn’t necessary to hide the materials menu, as there is enough free space on the screen. The lightning immune block makes lightning pointless because it always comes from the same direction, so I purchased one and I was done with that. Also at the third wave I experienced a bug where the attack count went negative and I got infinite disasters until my blocks were all gone and I lost.
The music was very pleasant, nice little game you got there!