Click on the Play button to begin.
Once you start, you will see you have 2 dots, blue and red, that circle each other, you must use your mouse (or finger) and click on the screen (anywhere) to make sure those dots only stop when they have solid ground beneath them. So you must time your clicks in a way that the dots will advance, each time stopping them only when there is ground underneath (or a wall to climb, as this game is three dimensional).