PSA: There's a dark theme and colour blind mode in the settings. Because they couldn't be arsed to make it accessible from the outset.
For non colour blind people (or this non colour blind person, at least), CBM is really horrible to look at. This is often true of CBM generally, not just of this game. It’s just an ugly* mix of colours.
It's quite hard to come up with a set of colours that work for all types of colourblindness. What works for protanopes can make things worse for deutaneropes, and vice-versa. And some people have true monochromatic vision.
Aesthetics are a lost cause. People with normal colour vision are obsessed with colour, and have all sorts of weird rules about what does and doesn't look nice
[1]. Being colourblind, I'm banned from making colour decisions without adult supervision. My sense of aesthetics is dominated by contrast (and I have weird protanope ideas about the brightness of anything with a strong red component, which is an additional liability), and I'll generally choose colours for contrast reasons.
Would it actually be possible to make a default setting that suits the needs of <everyone>?
Sure, you follow the simple design rule of not indicating anything using colour alone (I call this the "does it work in black & white" test). Different textured lines, shapes of boxes, crossings-out, that sort of thing. Then you can colour them in to your heart's content - remembering of course to stay within the WCAG rules on contrast - and nobody has to think about it. Using colour alone is just lazy design.
Making the word game non-tedious to screenreader users requires a bit more thought. Nobody wants to listen to "black large square, black large square, replacement character, black large square, black large square, replacement character, replacement character, black large square, black large square, black large square, replacement character, black large square, replacement character, replacement character, black large square, black large square, replacement character, black large square, replacement character, replacement character, replacement character, replacement character, replacement character", especially once they realise that it doesn't even convey the game state properly.
[1] Nobody has ever successfully explained 'clashing' to me. Apparently it's a thing.
