Great game. I played through the whole thing and made it to the end. I don't normally do that with game jam games. The spear mechanic is nice and refreshingly unique. You could come up with some fun puzzles with that.
This game is the roots of something grand I hope you don't give up. It reminds me of games like Hyperlight Drifter and Zelda. Add some more enemy types in areas and some extra puzzles and keep expanding content.
Also the boss looks really good. Is it 3D and everything else is 2D, how did you do that?