All you have to do is to jump on the platforms and avoid falling by jumping over holes. You have normal and double jump and you should use them wisely to progress. There is also a time limit and you will lose the game if you run out of time. So you must collect the clocks that you find on your way to increase your remaining time and be able to climb higher.
Touch on mobile device(touch left side of screen for single jump and touch on right side for double jump).
Use mouse or keyboard (left and right arrow key) on PC.