Oh, there were a zillion of these. Ball physics with gravity are easy/fun to make, so something like volleyball or tennis is pretty much everyone's my-first-game-with-physics project. No coincidence they've all got round heads :)

The one I remember playing growing up was some DOS volleyball game where you played as two hideous little purple Q-bert looking dudes. Looks like it even has its own Wiki page! Dates to 1988. https://en.wikipedia.org/wiki/Arcade_Volleyball

Ha, also in Canada and also played a lot of Slime Volleyball in school. I remember the graphics were pulled from a folder of jpegs or gifs, so I substituted all the images with pictures of my friends and other goofy things. Good times.