The aim is to cover the whole grid with the same color. You start having the top left block which you can give a color. Whatever adjacent (horizontally and vertically) blocks have that same colors attach and become active. The active region becomes bigger and bigger until you fill the whole grid, unless you run out of turns! I decided this would be a fun thing to make when I played an implementation of this inside Kolibri OS, though I don't know if that's where the game originated.

Music: Ambient guitar X1 - Loop mode by frankum