Hey, Michael here! I did the art and sound for the game.
As a huge Metroid fan, your comment made me smile a lot! :)
It was definitely a bit much but I'm glad we got as much done as we did!
I thought about Background ambience for sure but as you might imagine, I started working on all of Sound the very last hour, so there was only time for the absolute necessities and an emergency Piano (Which, at least to me, fits quite well in the game, surprisingly.)
Thanks a lot for your Feedback and kind words!