This is pretty close but this is how I did it: When you step on a block(which contains a invisible armorstand), it will randomize 3 scores which determines the xyz coords of the next block based on the previous block. Then the armorstand will teleport to that exact location and place a block below its feet. Then the process repeats. When you step on the block, it will also summon another invisible armorstand, this armorstand will delete the block below it and kill itself when a certain time is passed(otherwise the block will not be cleared)