YouTuber nesatlas beat the original Metroid in under ten minutes. Granted, it was tool-assisted, used save states, and door glitches to make it happen. That's not the cool part.
The cool part of this entire video is seeing the game played super zoomed out so you can see the map and levels in full. It's the first time I've seen the game played like this, making for a refreshing take on the classic experience.