Hi! This is a really fun game, but I'm encountering some bugs:
-On depth 8 and higher, sometimes void bricks will overlap with regular bricks and make it impossible to clear a section.
-Perks do not apply to the new game (or at least bonus starting currency) if a new game is created through "retry" when ending/losing a run. It works fine when a new game is created from the main menu.
-By having enough upgrades that reduce max hp (legendary or not) you can go into negative hp. (-10/-10)
Other than this, I've got a suggestion to add more stuff for fragments because using scaling (Streak runner or momentum) it allows you to gain thousands of fragments. Currently, I've got over 29,000,000 fragments and nothing to do with them. Additionally, momentum seems a bit underpowered compared to streak runner because by reducing ball damage you can get ~24% total score per brick rather than simply 10%+whatever score you own.
All in all, great game! I can't wait to see if you update it anymore.