Adaptation First: The Nintendo Entertainment System version of Metal Gear was the first version released in North America, as the original MSX2 version was never available in North America. Although technically a port, it has enough differences to be considered a separate game.
Creator Breakdown: Kojima didn't really want to make any sequels past the original Metal Gear Solid, and there were death threats against him after making Metal Gear Solid 3 because he didn't want to make a fourth game. As a result, Metal Gear Solid 4 is full of subtext about Kojima's reluctance to make yet another Metal Gear game and resolve story points he never intended to be resolved.
Kojima considers the NES version of the original Metal Gear to be a Porting Disaster of his original MSX2 game.
Zigzagged with Snake's Revenge as he has had mixed feelings about the game.
Franchise Zombie: Quite literally. After Hideo Kojima left Konami, the next game in the franchise, not including him, is Metal Gear Survive, a zombie game after he considered the franchise done.
Hostility on the Set: David Hayter has made it no secret he and Hideo Kojima never got along during their time working together. According to David, Kojima tried to get him replaced as Snake in practically each game since Metal Gear Solid, which eventually he did with Metal Gear Solid V: The Phantom Pain. Why Kojima disliked David is unknown, but it's commonly assumed that Kojima hated not having a big name actor playing Snake, due to Kojima's well known love of Hollywood and movies. Reportedly, when Kiefer Sutherland replaced David as Big Boss for MGSV, David was not even aware until after the fact.
David Hayter, English voice of Solid Snake, has been known to spend a lot of time saying "OhmyGodhotnessIwannaBANGYOU" and "CRAB...BATTLE...", references to two popular MGS Flash parody shorts.
Meme Role Reprise: David Hayter recorded a video responding to Vinesauce member Vinny's impersonations of Snake, particularly a Running Gag where Snake insists that Raiden "squeeze [his] hog" (itself referencing the infamous Crotch-Grab Sex Check from Metal Gear Solid 2: Sons of Liberty). In Hayter's video, he, in-character as Snake, states that he's aware of the bit and claims that he can only think of one thing to say in response: "Raiden, squeeze my hog!"
No Export for You: The MSX2 version was only released in Japan and certain European countries. It wasn't until its inclusion in the Subsistence edition of MGS3 that it got a wide release (particularly in America).
Recursive Adaptation: Played with the series as a whole. The series started out as a PC game (yes, MSX2), and in some sequels, ported to video gaming consoles, and then some of them even ported back to PC, and then a few of them consoles again.
The English voice acting agency got a bit lazy when it came to rehiring the original voice actors in spin-off titles. Most notably:
They're not great at continuing the actor allusions onto the English localized versions. In the Japanese version of MGS2, Olga and Solidus were played by Kyoko Terase (Meryl) and Akio Otsuka (Snake), respectively. In the English version, Olga and Solidus are played by different actors than Meryl and Snake, so the idea that both sound alike is lost. This also happened with the Optional Boss fight against Meryl in the Substance re-release. Meryl uses the same sound clips as Olga does in her boss fight from the main game, since they shared the same Japanese voice actress, which results in Meryl gaining an inexplicable Russian accent for the fight in the English version.
Solid Snake is voiced by Peter Lurie when he guest-starred in the third Ape Escape game.
Miller's voice actors in the Japanese and English versions are different between Metal Gear Solid and Peace Walker. This is justified as the former was actually an imposter.
In MGSV, Kiefer Sutherland voiced Big Boss, replacing David Hayter.
When they first started considering a Metal Gear movie, they used an image of Michael Biehn as the model for Solid Snake on the game's box art - anticipating casting him as Snake.
Kojima had wanted to make a crossover game between Metal Gear and Rumble Roses with Rumble Roses' producer Akari Uchida, but the Metal Gear team refused to work with the Rumble Roses team. However, Reiko Hinomoto and Rowdy Reiko, her evil alter ego, would eventually appear as secret characters in Subsistence's iteration of Metal Gear Online.
Snake made another appearance in Super Smash Bros. Brawl, the first revealed third-party character in the series. And ten years later, he would make a return appearance in Super Smash Bros. Ultimate.
about Kojima's reluctance to make yet another Metal Gear game and resolve story points he never intended to be resolved.