Bad grammar somewhere
Luigi was on a walk. On his walk, he found a pipe to an uninhabited island. Or was it? Luigi heard a noise!
Or if that doesn't fit use a cutscene like the second picture.
This image bothers me a bit on the bottom left part. It just looks wrong, and it seems cutoff.
In this image, you can press the switch, and do that spin while big glitch to get under the ground.
Other than that, the palettes are beautiful. Nice hack.