A chain reaction is when something triggers an explosive, which in turn triggers another explosive, and then another, and so on! Circles is about starting the right chain reaction that will clear the screen, which will allow you to move on. The game will contain (at least!) 90 level at launch, and will hopefully give you some pleasure and enjoyment for an hour or two. The music is relaxing and is crafted for Circles by the team's very talented musician.
A circle always has some filling, when you tap a circle you add some more. If you fill it to its edge, it will explode and debris will fly in all directions! Debris hit other circles and adds some filling and causes more explosions, creating chain reactions!