You have to use up arrow key to jump up & down arrow key to go under of obstacles or if you like you can use your scroll wheel to jump up & go under from obstacles. Try not to touch obstacles. If you touch them you will get out from the game. You can try it again. Come on let's try to do this!!!!! sorry to say that this i not mobile friendly :(
Thank you Kesuli 2005 the original project. Go check it out. https://scratch.mit.edu/projects/446852974