How "Colorblind-proof" should games be?

For consumer products in general: the more accommodations you make for discrete demographics, the larger your audience. That goes for likely all facets of design: colours, theme, mechanics, marketing, component fabrication, on and on. It doesn't necessarily make the game any better, but more people may consider it because you've gone to those lengths.

I remember walking through a big-box store many years ago, looking through children's toys, and noticing a specific colour palette on several different types of toys. "Everything looks like it's been soaked in mustard," I remember thinking to myself. But then I realized that a company had specialized in accessibility for infants and toddlers. It was a new concept to me, and I was ignorant of the notion - at least in terms of the world of toys for babies.

I've seen a lot more of these kinds of accommodations for computer games and software, likely because it's so much easier to change digital palettes on the fly, even to the point of using patterns.

Incidentally, I personally concentrate on using patterns for differentiating components between players in my prototypes, using dots, stripes, zig-zags, and the like. This way, print-and-play components with black ink/toner will still provide the needed differentiation.

Try to see how a color would look to several people. I think only yellow, blue, black and white are really useful if you want to have 100% of the people that can see. Of course, you can add red. But it has to be the one at the far end. Which can go wrong.

So find someone with protanope to see if red is different than yellow.

Also, adding white to yellow helps a lot. As long as the tritanope can still see a pink-isch color.

And blue has to be taken in such a way that it is also blue for the tritanope.

So, what do the people see?

Blue: blue, blue, dark blue
Yellow: yellow, yellow, pink
Red: black(?), dark yellow, dark pink (red)

But enough about colors. Use light colors. And add textures where possible.

We have a rule in user interface design that color should never be a source of information. You should have something else like shape and icons that contains this information.

For example, Magic the gathering, have card colors, but also a mana icon matching the card's color.

In board games, I know that many times, a player uses pawns and pieces of a certain color. First you need to determine how many players or factions do you want to have.

If it's more than 5, you should consider using icons. Britania is such an example where they combine colors and icons. But just icons could work fine. In my early design for fallen kingdoms, I also had 5 colors, and 3 unique icons each. My lime green and yellow card board looked very similar, so I had an hard time distinguishing between both. Since all icons where unique, it was not much of an issue.

For my color blindness, I see all colors, but when colors are similar to each other, it takes more time to differentiate them. It's another type of color blindness.