This is a great game as made for both the jam and your coursework, so well done on coming through with a prototype. It has easy to understand controls, solid gameplay loop, and fulfills the expectations of a bullet hell game through the wild frenzy of tennis balls.
As per previous comments, I found it difficult to hit the tennis balls back. This is due to the controls and speed of which balls are released. I personally would find it easier if the control was to press and hold "E", and if balls were released at a slower speed. It can also help to have the camera be fixed to overlook the entire arena, so that a player can more easily dodge and weave.
I'd like to see you explore some more fun bullet patterns as well.
Great job. Good luck on your developments!