This would have been neat, if used in a game... but as a prefabricated engine, it's just not the best example of something like this. It pretty much works like the usual overlay-based "sword engine," but has a swing attack too.

It uses a method of preserving the overlay by copying to a hardcoded visible area on the board. The swing attack works, just not as described. You have to hold space and hold left and right for the duration of the attack.

The overlay preservation trick is neat, but glitchy and could be done way better in modern Megazeux.