good game.
Something funny I noticed:
if you go to the menu, use q to buy maximum (even if you cant buy anything) game obviously does some calculations.
and, while doing that, it apparently keeps the balls last speed change value wise but changes it's direction!
like if I press m,q,m the balls will suddenly move with the same speed but now in a different direction than they previously did! :-)
Nothing game breaking but if you keep spamming mqm constantly, you can totally see the balls zigzag wildly around the middle and never really getting close to the walls cause their direction changes with each triple key press :-)
no real bug, just funny to observe.
you might NOT wanna recalculate the balls direction when q gets pressed but literally only do that during ball creation and after collision :-)