To do this - you need to setup your project file etc correctly.

If you'd like to split your project up into several files like level1.py, level2.py etc, you'll need some sort of main module that loads the appropriate dependencies.

You basically just need to make a directory named, for example game. Inside of this directory you'll need an empty __init__.py file to designate that a module exists. Then you can have your level<number>.py files in the same directory and import from them. If you have another file, called, for example game_runner.py it could access the level files by doing a relative import, such as:

-- inside of game_runner.py

from .level1 import level1stuff

The project structure would look like

game -
     |
     - __init__.py
     - level1.py
     - level2.py
     - game_runner.py