In this game you need to save reefs from destruction. Actually you need to create new reefs yourself to preserve the marine life. There'll be some kind of jellyfish falling from above. You need to catch these jellyfish and drag them onto free spaces on the rocks. If you succeed to stick a jellyfish there it'll become a corral once it touches one of the small color shapes that float in the water. To speed up th process you can drag these shapes to the jellyfish. There will also be harmful elements that will try to spoil your work. You'll need to click on them or drag them away to get rid of them.