ON. This forces the emulator to scale the original

Metroid: Zero Mission isn’t just a simple graphical update of the 1986 NES original; it’s a complete reimagining that respects the source material while introducing new areas, items, mini-bosses, difficulty levels, and a rewritten story that explores Samus's past. This delicate balance is what makes the game a "high quality" experience. It retains all the elements that made the original great, such as the core structure of exploration and its iconic bosses, while adding enough new material to surprise even veteran fans who know the original intimately.

Here is why Metroid: Zero Mission remains the gold standard for Metroidvania titles.