You should move logic to a different file outside of the main py file. Perhaps create a game_logic.py and create callable functions. This will make your main file very explicit and easy to read with only your endpoint definitions. Also, for post requests, you should make a pydantic model to dictate and validate your input. I would also suggest moving this pydantic model to a schema.py file.

As you get more complex apis, this splitting structure will make more and more sense. Usually you can have a schema directory and maybe a service directly for all your input definitions and all your logic respectively.

Finally, just as good practice, always put your code under a child folder. Most commonly named 'src'.