Use the green buttons as the arrow keys. Warning. This game doesn't work on desktop computers. Use the version for desktops if you want to use a desktop to play this. This is the URL for the desktop version. https://scratch.mit.edu/projects/458696941 Try to collect the crystals and you will see how many crystals you've collected in the top left corner. But, watch out, because when you stop the program (hit the red stop sign) you lose your score.
I used the idea from a lego set that I built and decided to make part of it in scratch.