The game looks squashed in origonal mode for some resaon. The classic NES Metroid seems find but the zero mission one has a squashed look, and those spiked round crawly things look unusal (not round)
You call it squashed. Those of us who live in the 21st century call it widescreen.
It is a little know fact that the GBA can also display images in 1080i. The process involves 3 teaspoons of olive oil, a brick, 2 eggs, a twelve gauge shotgun, 6 chickens and used bubble gum. MacGyver did it once.
Yeah, instead of the square 4:3 block format, it's compressed into a widescreen 16:9 block format (which would make a ROM difference between the classic cartridge and Zero Mission version). Even TileLayer Pro could discern this, maybe.