Neat idea. Some classic game design mistakes like not explaining things to the player: 1. what does upgrading axes and finding better quality axes do? doesn't seem to make them any stronger. 2. what is "spiky" and "hammer" and the other affixes?
AoE effects are generally not useful but could be improved by tweaking some combination of making the area bigger, doing more tick damage, sticking around longer, triggering more frequently (and these could be improved by upgrading/better quality probably).
I ran into a bug that made me unable to progress, I hit the home button and then "play" and then trees were invincible. They would take like 2/3 of their health damage, and then would stop taking damage. I tried buying different axes and upgrading and stuff and nothing worked and I could proceed. No biggie, I was almost at the end anyway.
Good job, hope you get a good grade.