Regarding Snake's Revenge, that's not part of the official Metal Gear storyline, it was only released for NES and was made by a totally seperate team by the name of Ultra Games.
Ultra Games = Konami
Back in the 80's, Nintendo had a system in place saying that a third-party could only publish something like 2 NES games per-year (I don't know the exact number), unless Nintendo's testing division said it was a triple-A game, at which point it was free from the system, and didn't detract from the total. You could make as many of those as you wanted (which was why everyone took Nintendo's "suggestions" about game-making so seriously).
I'm sure you can see the logic flaw in that system, since games take time to make, so you can never "take advantage" of winning a really good rating and making another game. You just had to always make more games than you were allowed to make, and let many of them fall under the axe.
Konami said "What if we were two companies? What if we make a division called 'Ultra Games' or something cool like that? Could we release twice as many games?"
Nintendo said "We'd see through something like that in an instant. But we like you. So we'll overlook it. Here you go. Ultra Games is now an official Nintendo third-party."
It's like how Fund-Q was supposed to help small startup developers, but then Yamauchi let Square get in by pretending to be "Game Designers Studio".
Of course, Ultra Games being Konami doesn't change the fact that Snake's Revenge wasn't made by Kojima.