Due to Pico-8 limitations the game uses 60fps flicker for a variety of effects (eg. semi-trasparency, font antialias, colour blending to have colours like cyan/teal not in pico8 palette), but in the web version the browser and/or busy pc could skip several frames making it noticeable/annoying.
In that case you can turn the flicker OFF in the menu pressing Enter (you'll immediately see the blending effects disappear -the ladders will turn blue-, crispy font etc..).
Thanks for playing!