Colorecall

Colorecall tests how well you remember a shade, not a colour name. In its main mode, Duo, two shapes appear side by side in two colours for five seconds. One of them comes back in a plain colour and you set its original shade with hue, saturation and brightness sliders, then lock it in. Holding two colours at once is the hard part, since they blur together in memory. The shapes are often familiar marks, such as a card logo or a letter, so the shape will not remind you of the right colour.

Each mode has a daily of four rounds with the same colours for every player, and each round scores up to 25 points, so a day's set is out of 100. The score compares your colour with the original in CIELAB, a colour space built to match human vision, so it reflects how different the two colours look rather than how far apart the numbers are. After each round the shown colour and yours appear side by side with their values, and a leaderboard ranks the day's players. Your name on it is optional.

Besides Duo there are three other dailies. Classic shows one shape at a time, and you pick the shape back and rebuild its colour. Flag shows a flag with one area painted the wrong colour, and you slide it back to the real shade. Football Logo does the same with club badges from the Premier League, Real Madrid, MLS and more. Quick Play gives new colours every time for practice.

The daily set turns over every 18 hours in the site's code rather than at a fixed hour, so the reset time moves from day to day. It is free in the browser on a phone or a computer, with no download, no sign-up and no ads seen on the page. It suits players of colour games such as Dialed or Hueman who want a test of memory as well as eye.