circle_outCircle Out is a SET-like game of real-time pattern recognition.

Cards have two colors on opposite corners (like diagonal dominoes), and your job is to find a “circle”, a set of cards that link around in a chain. Now that I mention it, couldn’t you play this with dominoes?

I thought the numbers might have something to do with the game, but apparently it’s just to help those who are colorblind (e.g. all reds are numbered 5).

The site also claims the game has something to do with economics.