I'm actually pretty happy to hear this :D
It was actually everything made for the JAM.
I previously (months ago) draw and made a brush in Photoshop with the bush and trees used in the game, so I can make the background tree and foreground bush with no time. And the background sky (you can see if you at the top of the level) I also have previously made, but everything else was made within the JAM time. All the rest of the art, including player, boss, animations, particles, sound and programming. That's way the character controls are a little sloppy :D
I'm so happy that you like it, thank you :D