The NES version wasn't popular in North America, so I don't think that a Turbo version would have helped. If the barrier of Konami PCE games being published in NA is going to be broken, there are already enough existing games like Drac X and Gradius II which would have had a much greater impact.
it seems that the original metal gear was moderately successful in the states, but after playing the first time on ps vita, it's seems so advanced compared to lets say bloody wolf or mercs.
but metal gear 2 : solid snake could of been a really big hit as it's like a slightly condensed version of metal gear solid thus way before it's time, especially if was a early release for tg16 lets say 1989
in regards to castlevania, the turbografx 16 /cd appears to waning in the states from 91 onwards anyway and later releases on pc engine such as Castlevania: rondo of blood may not be enough prop up the market against the onslaught from SNES and Genesis.
I'm not sure what you mean by "advanced". At the time part of what turned off the average player was how primitive Metal Gear was and how poorly the English version flowed. Regular people may have been aware of the game's existence because of the cover art and magazine ads, but it was very unappealing at a time when very few people played RPGs, sims and anything that wasn't more or less pick up and play. It is exactly the kind of game that got purchased based on packaging, leading to a disappointed child after they tried playing it.The Ultra/Konami brand sold and rented out many titles, regardless of content.
When MGS came out, the media had to explain what "Metal Gear" was, beyond 'that NES game with that cover' or 'that game game that didn't really go anywhere'. Bitd I had many friends who were "hardcore ganers" for the time and I was the only one who had both the drive and ability to finish it. When I got online in the late 90's, few people I talked to had played through the game or had good things to say about their experience with it beyond what I also felt: it was disappointing considering the potential it showed early on.
If you won't take my word for it about the quality of the game, maybe you'll listen to this guy:
I had absolutely no participation in the development of the NES version. The NES version was a pitiful title developed cheaply and simply by a small team in Tokyo. That was during the bubble economy where anything and everything that was released would sell. I came across the game in a bargain bin and tried play it, but the game design is pretty bad. There is some gameplay that includes infiltrating a base that didn't exist in the original. However, even I, the developer of the original game, was unable to infiltrate the base even once.
Furthermore, being Metal Gear, it goes without saying that Metal Gear should make an appearance at the end. However, from what I've heard, due to the technically difficulties in displaying the sprite on the screen, they swapped Metal Gear out for a gigantic monitor. That made me see that whoever created the game had no sliver of appreciation for the players. However, even thought it was an abomination, it was during the bubble economy and it sold millions overseas. That title has only soiled my reputation.
But if you're thinking about the infinitely discussed topic of changing history to save the TG-16, the only kinds of magic bullets after the first year would be exclusives of games like SFII. Even then, what the TG-16 needed to be massively successful was to kill off the Genesis within that first year by doing most things differently and luck suding with them.
I don't think that MGS is really a good game and is only worth playing through once. Even a great stealth game for 16-bit consoles would be more of a novelty than a game changer though. We got stuff like Silent Debuggers which went under appreciated. The same would have happened with a decent original Metal Gear game