Thank you all for the great feedback and comments! <3
@chrisantem 44644 is the highest I've seen so congrats to your friend!
@dining-philosopher That sounds strange. Did you only cut the first stage of the trees? The only thing blocking the lava is water which you spawn by cutting down all stages (last stage is palm trees).
@extar Hm, didn't it zoom out revealing more trees as you cut them down? Eventually lava should erupt which gets slowed down by water. The more you cut down the faster things grow and the bigger your cutting radius gets. So the goal is to cut down as much as possible (through all stages of trees) and create barriers of water.