Nice menu, although I would love to see a volume slider.
Good music and sound design, I like the combat sequence and the UI is very clean and functional.
The world design is very good, very unique style with the world curving away from you. The choices for the environment and the path keep the routes clear, but still visually appealing.
The controls are quite good, except perhaps holding 'w' could keep moving the character forward.
The sounds for all the monsters are quite charming.
The combat itself is rather repetitive, the simplicity of the system means that the monsters can't have much variety. You could add some visual numbers to the various systems - a player might start to worry when he sees the slime has +20 health compared to the frog. And again, if you showed the player exactly how much damage the enemy was doing to you, you could maybe begin to worry that those wasps are doing more damage than you expected! If you let the player see the numbers and start to do some of the maths in their head, then the combat can be much more exciting without getting much more complicated.
The upgrade path was nice and rewarding. Would have liked to see the cemetary enemies do more damage and the player be able to do more damage too, because it takes a bit long to do those battles.
...had a crash... good thing there's a SAVE SYSTEM! Nice. (think it was to do with loading the cemetary then going back to do the cave... yeah I just had another crash. Seems to happen if you load a level and then go back to the previous level and win a fight)
Unfortunately I couldn't progress past the cemetary because of the aforementioned crash. Shame!
Overall, generally good execution, everything is to a high standard and besides a few bugs a pleasant and enjoyable game!
Also, thanks for putting on the jam! Was a bunch of fun.