Colorblind Information on Product Pages in Store
A descriptive information field when purchasing games digitally from the store (and possibly on physical copies as well) under the Capabilities List that states Colorblind Accessibility Yes or No.
I believe having this as a description that developers would have to submit with the game might remind them to incorporate colorblind options with their games. Many devs forget about colorblind players even though there are a lot of us.
There are many games I wait to purchase until I can find out if colorblindness is going to cause an issue, especially PVP team shooters, RTS, and card or board type games.
The best colorblind friendly games let the player choose the colors that indicate the teams or vital information (like Battlefield 4). That is made even better when a game also incorporates Icons that identify teams or important information along with color. Some of the worse games for colorblind players use whole screen filters which just don't work very well at all.
It's always a bad experience when you get a game and can't play it, or when you shoot all you teammates because you can't tell which color team you are on.
Not just colourblindness, but accessibility information across the board.
There's a sliding scale of how accurate information can be, for example 'colourblind friendly' doesn't indicate whether it is filters or symbols, whether it's safe for everyone or only for the commonly known about three types, etc. And a game that developers genuinley think is accessible may in fact not be.
But still, any degree of extra information is still helpful. Even itch.io's which in part due to the type of developer submitting (lots of students and language barriers) is really innacurate has still proven helpful.
Another example of it in action is on steam, where games can be filtered on whether or not they have subtitles. Again that does't tell you how much of the game is subtitles or how the subtitles are presented, but it still makes browsing a bit easier.