For me, it's the arrow keys. I have also noticed that if hardware acceleration is active on PCs it runs at like 1.5x speed, making it much more difficult. I may add a note in the description to warn for that.
Oh I might be confused. I use a 60% keyboard so arrow keys are either Fn+WASD, or I can switch into a mode that makes them into perma-arrow keys. I may have been in that mode at the time lol
The creator of the engine, Lobster, is adding WASD integration. If you are interested in the engine, he has a discord that is link on the Pocket Platformer page.