Given your interest in a comprehensive collection for PC, I recommend checking the latest offerings on digital storefronts like Steam, GOG, and Humble Bundle, as well as any potential re-release announcements from SNK or game publishers.
The notation "1234567x" seems to suggest a desire for a complete collection up to . As of my last update, there isn't a single package on PC that includes every game from 1 to 7 in one go officially. However, purchasing individual titles or specific collections should allow you to play the entire series. metal slug collection 1234567x pc comple best