Hey, @tomcat94! Thanks for telling me that... sorry, my bad. I will update the page for the instructions.
So, these are the rules:
Everytime you press a direction, the elements will try to move into that direction, unless it has reached the edge or is blocked by another element.
Whenever an element is blocked by another, the elements will try to interact with each other; such interaction can happen in 2 ways:
1 - You will merge 2 elements if they have the same color and level (number).
2- You will destroy an element if the incoming one has elemental strength (as shown on right panel) against the destination element, as long as the incoming one has a higher level.
I hope that helps clarify the rules. If it doesn't, please let me know. Thanks!