A downloadable game
One day, many years ago, I was at my grandparents' house. They had an Apple Macintosh computer, on which there was a game called "Barrack" by Ambrosia Software. I thought the game was one of the coolest things ever, and when I got home, I was unhappy that I could not play it, because I did not have a Mac, but a PC with DOS/Windows (3.1 I think it was at the time).
I found some game called "Jezzball" on the internet, but even though it employed a very similar gameplay concept, that game lacked the variety of different ball types and I thus found it boring compared to Barrack.
Having no other way to play the game, and being the avid QBASIC programmer I was at the time, the logical solution was to program my own version of the game.
Since it is a DOS executable, you will need to use DOSBox to run this game (unless you still run DOS on your computer, in which case you are pretty badass).