Is it just me, or is this for many people more a test of

a) your capacity to stare at a screen without tearing up, blurring, etc.

and

b) the quality and color profile both native and gamut-corrected etc. of your monitor?

I swear this is much more a test of my current monitor settings vs. ambient light conditions, than anything serious about my own color perception.

A physical version with color chips and the option to work under a variety of lights (LED, halogen, CF, incandescent, sunlight...) at whim would be way more revealing.

But yeah, harder to code in JS.