[nomilk]

Try to pick more intuitive colours if possible. My first guess had both dark and bright red, and I wasn't sure which were closer/farther (had to reopen the site in incognito to get and read the instructions again). A more intuitive gradient (perhaps between just two colours, e.g. white and red) would remove the need for instructions.

[b0r0phyll]

You can tap the question mark in the top left to see the instructions again! But yeah, I can see how the color scheme might be confusing. As Kluggy suggested, I might add a gauge on the side of the board which should help prevent that mistake