Awesome game and super cute art! Picking up the orbs was very satisfying and the U-Magnet was easily my favorite pick-up item. The grenade effect of seeing the level below was awesome and very well done. A neat little extra detail I enjoyed was the edge of the world being the edges of the book. I felt the double grenade upgrade worked against me more than helped as it would trap my movement, but the extra line shots were very useful.
I loooooved the boss fight and I'm impressed you had time in a 9 day jam to include it. It made for a great climactic moment.
Overall, top-notch entry!
P.S. The boss is named Bruce Inksteen? Har har har