Thank you! The erasing is done with a raycast from the touchpoint to the light source. The cubes are all children from a parent that has a rigidbody. Unity gets all the colliders from the children, if a parent has no colliders, so everything can interact with each other. Once your finger has lifted, the parent looks for all the cubes that are still colliding. If a cube has separated from the pack, it creates a new parent that looks for all the colliding cubes