The stages in Metal Slug 7 are exceptionally large compared to older titles, offering a more extensive journey.
Before its financial restructuring, SNK moved its arcade developments from the aging Neo Geo to Sammy’s arcade board (and later Sega's NAOMI system). Metal Slug 6 was actually released on the Atomiswave.
Metal Slug XX is natively available on Steam with full controller support and achievements.
Metal Slug 7 Neo Geo ROM: The Myth, The Reality, and The History
Here’s a concise piece for you:
Available digitally via the PlayStation Store.
You will need a .nds ROM file extracted from your legal physical copy. Metal Slug XX (The Definitive Edition)