Tsonncou

If the controls do not work upon running the program, click on the app window with a mouse or touch pad to focus the window.

To skip levels:
Press 'o' to go to previous level (except if starting at the beginning), press 'p' to go to the next level.

On Mac:
If the app cannot be opened because a message pops-up which says "unidentified developer". Go to Security and Privacy > General > override yes (to open).