Ok so to be fair I am not sure how useful those modes are for other colorblind people, I’m just talking about my experience and to me they make no difference, I’ve tried multiple modes, even though I know I am red/green colorblind the relevant filter makes little improvement over my experience.
I can barely tell the difference on the rare vs epic drop color, but enabling the filters does little to address it or it just makes other color combinations harder to tell apart.
I’m not giving specific examples, because
a) I don’t remember the details since my experience is from the launch and I don’t remember specifics, just the general impression, currently I am playing without any filters
b) specific details about colors are beyond my point
And the point is that please consider making other design changes to improve colorblind experience, to give some good examples from 10+ years ago when I was playing wow, enabling colorblind mode made it so gold/silver/bronze had letter indicators G/S/B that is one example that actually makes a difference with color blind mode on.
Basically, instead of doing color filters, do things like distinct shapes forms and contours.
Another good example of that would be Dota(1/2) heroes, you can make them completely black and you can still instantly recognize them from their unique shape. Also changing things like green/red dots on the mini map become blue/red is also a better approach than applying color filter to the whole game which might worsen things in other areas.
These examples do not translate well to NW since there is no gold/silver/bronze or different races/heroes, but I am sure there are plenty opportunities for improvement, I acknowledge it is way more effort than a color filter and is very unlikely to be implemented.
My primary concern is I can’t tell the quality of the drops apart quite instantly especially if the picture of the item takes more space and there is little color left on the icon background.
Some things I can think of to improve it:
a) customizable quality palette, pick custom color for each quality
b) create distinct item icon frames for different qualities (like simple border for common, and some vine entangled border for legendary or whatever, you get the point)
c) introduce “quality markers” and stamp them on the item icons once colorblind mode is “on” (for example it could be something similar graphical icon as for monsters with the \\ /// vs \ // vs \ /, of course you don’t want to confuse players by implying that these types of monsters drop this type of quality, I get that there are a lot of things to consider and it is hard).
For the drop bags on the ground, I can also barely tell what color drop that is, so it could make a distinct sound on the drop event based on the quality (maybe it does now, but I can’t really tell if they are different) or make bags of different shapes or not bags at all.
For example, common - a bag, rare - a small crate, epic - a chest, legendary - golden chest. Again, I understand these have drawbacks like immersion, a chest or a crate is difficult to conceal for those who care about things like that.
I am pretty sure there are more things to be improved, the things that I’m not even consciously aware of at the moment but would improve the experience considerably if they had other visual cues besides colors.
TLDR:
please try to not rely on color alone to make things distinct, always use secondary visual cues - form, shape, icon/letter indicator, contour, border etc.