Could have potential for one of these flappy bird like rage mobile games ;D
Maybe with some adjustments on the camera the player can get a bit more vision over what is coming towards him. These "balls" at the later state of the game felt a bit more like.. run and pray that u dont get hit^^
There could be an indicator an idea that warns the player that there is something to spawn, so the player can react and try to avoid it.
Overall good work :)