Update

• I've updated the collision system again. I think it is an improvement but having 1,000 balls on screen is still going to be sluggish (worse for the web version).
• I've added more Achievements so there is now a few different things to aim for.
• There is now a small chance that each level a clickable Power Up will spawn. This is independent of the Power Up credit you have earned (they're free basically). I added this for people who like to play more actively. 
• Some price balancing. 
• Each prestige now adds $50 to your starting money, so you can get rolling quicker.

I'm not sure how much work will go into this game as I'd like to move onto some other ideas. Please do let me know if you experience any issues though!