These “upgrades” go to a maximum of 100 and become available after reaching stage 1m.
They all increase the difficulty of gameplay in some way but also increase the chance for a blue coin drop from a boss after 1m by 10% per upgrade.
They will be based on a timer so you can buy a few at a time. There is no way currently to remove or turn them off but I will probably add a way in a future patch.
Trackball Mouse: Increase minimum stage time by 10
Abandoned Mall: Faster max enemy movement speed
Cassettes: Increases max number of enemy shots per set.
Walkman: Increases fragment cost to open rifts by 1.
Rubiks Cube: Decrease player Regeneration by 0.66%
Fax Machine: Increase enemy spawn rate