Thanks for playing, matte!! F1 on keyboard and up on the d-pad if you're using controller will go fullscreen. The spawn animation allowing you to move was a bug we couldn't figure out in time. We're hoping to fix that soon and get a new build up.
I think this might be the part you're talking about in the screenshot below! If so try this instead: hold k > release k > hold J at the peak of your jump!
But thank you so much for the kind words!!