I made these toys for fun in high school (2011 and 2012) using Java's graphics libraries. None of the code is published because the quality ranges from unpolished to shitty. For my programming work, see Github.
Partially-implemented game of Tetris. Pieces are represented as in this diagram.
Issues: completed rows don't go away, pieces don't automatically move down, and new pieces aren't very random, but it is otherwise playable. In this video you get to see how bad at Tetris I am.
Partially-implemented two-player chess with mouse control. Capturing is implemented but not shown in the video for some reason.
Issues: every piece can move over each other, queen's movement isn't implemented, and there is room for improvement on the graphics front.
A toy to simulate string art, where string or yarn is threaded through holes in a sheet to make interesting patterns (example, scroll down). Instead of a continuous 'string', line segments connect two different colored dots.