A Chess game and engine on the Python-command line.
Link to GitHub. This project was later followed by ConsoleChess and then Pugs versus Bears, both of which are written in C++ and more powerful - the differential in speed was quite noticeable.
This version averaged about 30 kilonodes per second on my machine (i5-9300H), versus about 2.000 kilonodes in C++. That said, there are potentially some improvements than can be made to the Python-codebase as I was more performance-conscious when designing the C++ algorithms.