METAL GEAR / Konami / MSX
Though both of Hideo Kojima's original Metal Gear games were popular, they were also only released for the MSX, a computer system that gained very little traction in the English-speaking world. Konami decided to port these games to the NES for a Western release, but bizzarely, they handed them off to one of their "B" squads to develop. This less-experienced, less-talented team made all sorts of changes, the vast majority not for the better.
So there was always a certain belief among Western gamers that the MSX Metal Gear games - legendary beasts we had no manner of playing prior to emulation and fan translation - were vastly superior treasures that we had been unfairly denied. But while the first Metal Gear game is indeed better than the NES port of the same name, there's not really as vast of a difference between the two as you might think.
The game opens with Snake swimming up a river to the front gate of Outer Heaven, instead of parachuting into a field somewhere, but once control is handed over you quickly find that the gameplay engine is virtually no different than that of the NES version. The layout is a bit better, and it has a few more clever tricks and inventory items, but for the most part it's the same clumsy short-range punching and laser-vision guards seen in the NES game.
The advanced stealth mechanics found in the "Solid" series are nowhere to be found in this original title. No radar, no crawling, no wall-pressing, no knocking on walls. The guard field of vision is pretty much limited to what is right in front of them, but this is counterbalanced by their instantaneous shrieking of a horrible warning noise the instant they spot you, which then forces you to subdue anywhere from 4 to 8 guards (no hiding spots or "caution" countdown either) to put an end to the alert state.
Don't expect much in the way of writing either. Dialouge is largely limited to the occasional pop-in by Big Boss warning you too late of some upcoming danger. No dramatic boss death speeches, and only one major plot twist which the Solid series has likely already spoiled for you.
The only real difference between this and the NES version is that the layout is more thoughtful here and there's at least the rudiments of an ongoing story to accompany Big Boss's periodic "I FORGET TO TELL YOU SOMETHING!!!"s. It's still the same clunky combat and bad AI guards, however. Innocuous-looking trucks that you can jump into that take you all the way back to the beginning of the game automatically are a terrible design choice and a big reason why this game gets only a mediocre rating, as well as the bizarro save/continue system which only lets you pick back up when you've switched floors or gone from one building to another (it's never clear when you save and pick back up how close you'll actually be to the point at which you saved the game.) Does have pretty good tunes though, but even that's tempered by the hideous transceiver noise and the annoying typewriter sound of the text.
* Gameplay Video