If there is one stealth game that can hold up well against the original Metal Gear Solid then it would probably be Chaos Theory. The atmosphere, sense of awe and the sure amount of epic appeal make this game stand high above the stealth crowd, even above some of the Metal Gear's to be honest with you. Remember when the first Splinter Cell came out, well Chaos Theory was still in development, and the truth is, Chaos Theory began development even before the original was finished, pretty amazing, you would think that the original would have been more advanced in terms of graphics, engine and gameplay, but I guess not. Funny thing is Chaos Theory turned out to be the better one, and to be honest with myself here, I think that Sam's third outing has more of the making of an original than the original does, and not to mention it has a better and even richer story, as well as no plot holes what so ever, just play the game with subtitles and you will see what I mean, than play the original with subtitles as well and compare the two.
Overall, Chaos Theory is an outstanding game that will test the stand of time for many years to come, and in my book it's the best in the whole series... Bar none.