Catnect Four started as a JavaFX programming assignment: build a working Connect Four game.
Somewhere along the way, plain colored tokens became animated cats. Then the cats needed character selection. Then sound effects. Then a winner animation. Then smoother dropping animations. At that point, the reasonable thing to do was obviously keep going.
The finished version includes selectable cat characters, animated game pieces, custom sound effects, winner animations, and a UI built entirely around the very serious competitive sport of placing cats in a grid.