I had issues with the checkout spot as well and had a glitch that dropped me to around 5fps (guessing) then launched me out of the first person world when I exited the game into a pure blue void.
That said! The colors, art, dithering effect, are all GREAT. The premise of goofing off on your job by playing a game while dealing with customers is great. The platforming mechanics are DIALED IN. Would love to see this expanded into a world full of gameplay, upgradeable shops (perhaps?), unlockable color palettes, etc. It's lovely