"The UFO can only break through a block if the block below it is the same colour!"
So if the block below the UFO is red, you can break through the red block above the UFO
Red Block | Blue Block | Green Block | Yellow Block |
<Position 1> | <Position 2> | <Position 3> | <Position 4> |
Red Block | Yellow Block | Blue Block | Green Block |
In the example above, the UFO can only go up if it's in <Position 1>
Hopefully, this makes sense. Let me know if you need more clarification :)