Successfully tested multiplayer online platformer. You control a rectangle that can jump around a level made of square tiles along with other players. A friend programmed the level editor.
Video demonstration (this was most of what we managed): https://www.youtube.com/watch?v=c2hPXMTiFDw&ab_channel=TheTNTsheep
Files of interest:
client code - client0.6.py
server code - linux-server/Project_Quantum_Server.py
physics engine (collision detection between player and tile) - linux-server/collidePlayer.py (this will need to be re-compiled for your system using cython).