A cool concept, held back by the unfortunate tileset disappearance. Trying a different genre than you're used to always adds some extra learning curve time, so the short jam time always feels that much shorter. It almost always ends up feeling worth it though as you can apply your newly learned techniques to your future game ideas. Well done with the time given!
One major quality of life improvement I'd like to see if you choose to continue this project, is the ability to open and close the build menu with a key press or with the right mouse button. I found myself not being able to collect resources just because the menu was open (I'm sure the lack of a tileset made it even worse since I couldn't tell that I had a tower selected, so partially would be fixed along side that).
On another note, the walls didn't seem very intuitive to me, maybe if they were place on the actual pathway instead since it already stops the enemy movement? Or (just throwing out a random idea) maybe it could require that 3 walls be built, one on the path itself and then one on each side to form a full wall. The catch is that once it's broken all 3 are destroyed and so you need to build a new set of 3 to get your wall back.