I didn't understand but cookies are great \o/

I think you should remove the "counter" part (attack x1.5) it's hard to remember what type is strong against what type and what type is every monster. Instead I think it would be more fun if monsters had more various behaviours like changing lines, attacking other lines, going fast or slow... and the player would have to build a strategy based on behaviours instead of types. Or reduce the number of types and make them more obvious what type the monsters are based on their appearance.
I don't understand the difference between locked and selected. When I click on a tile which is not adjacent to a clicked tile, it should unselect all tiles except the one I clicked on. Also, a pause button would be great.
The way the effects are unlocked make it more efficient to always spawn the same monsters whereas it's more fun to try to make a lot of different monsters.
Looking forward next version. Good luck.

Interesting game and concept. It would be great if we could just keep space pressed once we pick up a crate to directly start charging it or make it charging automatically without having to press space

You should make the character jump on mouse release, because if I press the mouse button for too long, it refuses to jump and it's annoying.

Good! I'm looking forward the completed song

If your dream is to become a composer, I hope you have the will to achieve it ;)