just some ideas. include a prestige system. all but base bumper has to be bought by prestige. bumper level is caped and can be extended by prestige. numbers count on board is caped and can be extended by prestige. max multi a number can get within one fall is caped and can be extended by prestige. canon upgrades can only be bought with prestige.
show splitter and reshoot level in the bumpers.
maybe add small walls that can be bought. but they should be very expensive.
add shop/prestige etc to the ui, i dont want to always press tab to open the menue.