Originally Posted by cherokeesam
Why the hell wouldn't a prequel count as a sequel? Yes, chronologically, it comes *before* the previous movies, but it still creates an ongoing saga, just "in flashback," so to speak. "Star Wars: Episode One" came out after Ep. Six, and yet nobody out there would rationally claim that there aren't six movies in the Star Wars saga (....so far).
It doesn't count because of the context of which the OP is implying. If you actually read what the OP wrote, it's clear that he means a fourth film like X-Men 4, Spider-Man 4 or Iron Man 4 would be. Since X-Men was the first movie in its series, in the context of which this thread was made, any prequels should only count as -2, -1, and so on. The Star Wars prequels, in the context of which this thread was made, should only count as -3, -2 and -1, while the originals should count as 1, 2, and 3. So no, there has not yet been a true #4 Marvel movie yet.