Rapid Run is a fairly easy way to test your reaction. The blue square moves from the bottom of the screen, but red blocks constantly block its way. They appear now from the right, now from the left. Now one by one, now in whole groups. You need to deftly maneuver, also changing direction, literally slide into small gaps between dangerous blocks. To get away from the collision. Everything is simple and complex at the same time. Be on the alert all the time, do not lose your vigilance, just one smallest oversight will lead to the fact that the red blocks will win.