This is a Metroid II color hack. Not much to say here, besides that it looks absolutely great. Some glitchy looking area transitions and flickering during the final boss, but I'm not sure if the hack is at fault. I first played this several years back but I thought I'd revisit it as an easy way to start uploading again.

Hack link: http://www.romhacking.net/hacks/175/

Metroid II DX by Metroid Evolution