A demo of Metal Slug (Mission 1) for the Atari ST was released a while back by a developer who showed how the Atari ST platform could handle this demanding of a game.
You'll need an actual STE or above. Or you can use either STeem or Hatari emulators to run it. This video covers the settings needed to run it smoothly, including a couple of tweaks to eliminate any flickering.
For complete instructions and a walkthrough
watch the video below