This was fun! I was able to run through and prestige within a few hours, and generally if you like idlers this is something you'd enjoy. I've prestiged a couple times now, and I'd certainly keep playing if there was additional content added!
I do have some feedback for improvement though if you end up making updates. For UI/UX:
- Most importantly - I almost didn't play the game because I didn't understand that you have to equip the trees in order for them to show up (this may have been said in a pop up, but I have a tendency to click through pop-ups). This is a fun and unique mechanic, but that also means it's not intuitive to users not familiar with your game. I'd recommend adding some sort of forced tutorial to show that mechanic off.
- My confusion was compounded by the fact that you can't just click enable the item within the inventory - having to drag the item into the empty slot was unintuitive because slot ordering does not matter in this game. Adding that click enable would really help.
- Another UX thing that would make this game more polished would be some helptext showing an axe's ability while hovering over it. I couldn't really remember what each axe did, and navigating the skill tree was tricky after everything had been bought (I realized while writing this that the green axe helps trees spawn more frequently, that would've been nice to have remembered during the presige grind).
For gameplay changes I think you should consider:
- Decoupling tree hitpoints with the number of logs you get (having 9999 green logs take far longer to get than 9999 white logs is strange).
- Adding either 1 slot or 2 slots every color upgrade consistently (currently I am picking random things to unslot when I only get one new slot on upgrade, which isn't super interesting strategy wise),
- Having the different color trees have different abilities rather than just hitpoints
- Having coins do more than just get duplicate axes (like across the board have trees spawn faster or drop more logs/tree).
Good luck with further development of this project!