A really neat concept and fun game, but with a few caveats:
1. upgrades seem to stop working at a certain point - between leveles 3-4 my bullets just stopped exploding and max damage for all weapons got capped at 7, with the odd 11 thrown in here and there
2. it needs more upgrades and weapons - at level 38 there isn't that much more to upgrade, while enemies get harder and there is more of them
3. you can get stuck in the terrain, I almost died when some piece of terrain on the floor wouldn't let me pass, and it was so small that you almost couldn't see it
4. an autodigging upgrade would be nice (hold right-click)
5. enemies hitboxes need tweaking, since you have a isometric camera it kinda gets hard to hit enemies at certain points because you need to be aiming at their legs, and it's not always easy to find that point
6. a map would be great
7. crystals are almost worthless at level 38 with max double gain, you probably need some other form of XP gain on later levels
8. why no XP gain for monster kills?
9. my crossbow wouldn't auto-reload at a couple of occasions, I had to manually press R
10. Keyboard rebinding would be great
11. Enemies can spawn under you and damage you, not ideal...
This could easily be a 10$ game and you could sell a couple of thousand of them on Steam if you manage to polish it :)
Good job!
