In my opinion there are clear and simple reasons why Gladiator succeeded so much better than Alexander (other than the fact that the hero in Gladiator was straight). I'll lay them out for you.
I agree totally that there are a million details that would make wonderful scenes -- Alexander pouring the water out of the helmet in the desert is a personal favourite -- but a movie or a book has to work as a whole, not just a series of scenes, or else people won't turn the page or stay awake in their theatre seats. What was the main complaint about Stone's Alexander, other than the right-on-cue braying of the homophobes? That it was not coherent -- that it didn't work as a whole. Read the reviews and over and over you'll see the same word: "mess."
Are you familiar with Joseph Campbell's framework for the hero's journey? How he has to go into darkness from the beginning, and prevail against increasingly severe testing (making use of the other standard elements), to emerge the hero -- supplying the increasing tension, climax and denouement that are standard in plots? It's a trope that survives across millennia. Predictable, yes, but people still thirst for it -- over and over and over. Gladiator followed the basic framework, as did the three original Star Wars movies (Lucas had Campbell's book at his elbow while he did the screenplay). Lord of the Rings... Wizard of Oz... The heroic Greek myths such as Theseus and the Minotaur, Perseus, Jason, etc. ... each Harry Potter book/movie... I could name scores more. Once your eyes are open to it, you see it everywhere.
But despite Alexander's hero status, his life did not follow it except episodically. Each battle, each setback, is a mini-version, but over the whole course, he doesn't go into darkness at the start, his situation does not become worse; instead he goes into gradually increasing glory. When he does go into darkness -- the killing of Kleitos, the army insisting on turning back, the Mallian arrow, etc. -- it doesn't happen in a clear and well-defined way, so that some argue it didn't happen at all -- and he doesn't prevail in the end, as the classic hero does, but dies. To try to get the tension/climax/denouement pattern out of it, you simply cannot tell it linearly, you have to twist it around into knots as Oliver Stone did. What is the climax of Alexander Revisited? The assassination of Philip, paired with the killing of Kleitos -- though you could also argue that it's the point where Alexander gets shot and Boukephalos gets killed, leading to the denouement of the army turning back, though even that is not a final denouement. See, I'm not even sure, and normally you can tell where the climax of a movie is.
Stone was also trying to follow the tragic trope -- a natural, with Alexander dying so young -- but the resolution of his death doesn't lead right off the climax as it does in that trope. So it turned out, as the reviewers say, messy. (A related factor about tragic endings, which might have a lot to do with why Alexander did better outside of North America: statistically, on average, Americans like happy endings. This is common knowledge in the publishing industry. They also don't like things that are dark, except in the horror genre. I kind of found this out the hard way.)
It's also a fact of storycraft that you have to make your audience care about your character(s), and that is not possible without their motivations being clear (which they are, of course, in the hero's journey trope). Russell Crowe's character's motivation is searingly clear throughout Gladiator, yes? But with Alexander, it's not. What drives the guy across the world? There's a hint that it's to run away from his mother, but that's not convincing. Why is conquest so important to him? We're never told. Why is Hephaistion so important to him? We're never told that either. People wrote repeatedly in reviews, "I don't care about Alexander or any of the other characters." The hero in the classic hero's journey we always care about, because we can easily relate to his situation. But Alexander's life doesn't follow that.
Yes, there are too many events to contain in a single movie, but that's not true of a novel, or three novels, as has often been done -- and yet, more often than not, they fail. If Alexander's life had followed the hero's journey pattern, a movie director would be able to skim over events quickly and we'd still understand their meaning and the thing would still work as a whole, because human beings have an almost instinctive understanding of that story. But it doesn't, so you can't.
Well, here I think you're agreeing with the first part of my point, which is that to get something sufficiently interesting, you have to look at his life outside of the battles. Because the story of his battles is one win after another -- so that after a few it's repetitive -- and a slow and steady increase of his power. Let me put it to you this way: if a businessperson from a middle-class background works hard, markets well, makes good decisions, and steadily expands to having assets of $10 million, it's a great career and much admired. But does the story of each strategic move, acquisition and expansion make the paper? No. If someone dirt poor wins $10 million in a lottery, on the other hand, it does.The subject matter of a movie can be as pedestrian or as fresh and exciting as one seeks to make it. There's plenty of Alexander's life outside of battle, to include his pilgrimage to Siwah [etc]
Or -- let's translate the hero's journey into military terms. Hero's country goes into the darkness by being invaded by baddie empire, and conquered, or all but. Hero raises army, and through his and the army's heroism, prevails in the ultimate test by taking the country back and perhaps even conquering the baddie empire so as to rescue its people from their nasty emperor and remove the danger permanently. We have, of course, a real-life example in WWII (at least from the Allied perspective) -- and think of how many successful novels and movies, not to mention non-fiction works with big sales figures, came out of that.
But that's not the shape of Alexander's campaigns. Makedonia was not an underdog when he came to power, even if some advisors thought it was, due to the death of the man who'd led it to success. The army hadn't up and died, or lost any of its bravery or skill -- all it needed was a general of equal caliber to the one it had lost, and it had that. (Philip's early story is closer to the hero's journey, actually... with Makedonia weak enough that he was a hostage in Thebes as a youth, his brothers' throne usurped by a regent whom they then had to kill, his two older brothers getting killed so he ended up king, and then him coming back so spectacularly... jeez... someone should do a novel or a movie about that. But the poor guy is always overshadowed by his darned golden boy.)
I should really say that I actually don't disagree with you that a good Alexander movie -- no, trilogy -- how about BBC miniseries? (too bad Mel Gibson cacked out on the 10-hour HBO one he was going to do, based on Renault) -- is possible. Never say never... the moment you say something's impossible, someone comes along and does it Book or books, for sure -- I have to think it's possible, or quit writing mine. What I'm saying is that there are very big natural, structural obstacles, and Stone, though he made an admirable try, didn't steer his ship around them... the only one who ever really has is Renault. (Oh, and Pseudo-Kallisthenes or whoever wrote the Alexander Romance, but that was a work in a different genre (fantasy) than we're talking about (historical).)
More anon. I have to thank everyone, Phoebus especially, for this conversation as I'm using it to order and elucidate my own thoughts...
Warmly,
Karen