First off, this game is amazing.
Second, I have some suggestions.
1. Easter eggs, like walls you can go through (maybe the playable 2D version?)
2. Game over screen could be more interesting, like a 3D Pacman doing the thing where the wheel of his body folds in on itself.
This is so scary, great for people who are afraid of being cornered.
Things that would make this game better: 1. Auto-Upgrade button for media 2. Being able to change the amount of items you're buying, instead of buying each thing individually.