I think this is a pretty nice concept, basic but still fun. The increase in velocity of the fireballs is solid, although I feel like the quicker they get the rarer it is for them to bounce off each other which I found to be an interesting component earlier on. Maybe less speed and increasing the rate that they spawn would make for a more chaotic and interesting challenge? Music is nice, would be cool if the tempo increased with the speed of the balls shooting at you. Needs sound effects too, at the very least for the balls bouncing off the wand, and possibly others for when they get shot or bounce off one another. Great foundation though and I'd like to see you develop it further :)