An obscure, not terribly interesting Marvel comics superhero played by an actor who was famous for being a hot fuckin' mess should've amounted to an embarrassing failure. Instead, this little Iron Man flick launched an entire universe that's still going strong 10 years later.

Of course we're talking about Iron Man, directed by Jon Favreau. This still holds up as solid popular entertainment. But it's especially remarkable due to Robert Downey Jr.'s performance as industrialist turned armoured-avenger Tony Stark. His irreverent and quick performance, smartly complementing Favreau's unfussy direction that prioritises verisimilitude over ludicrousness, means that even though the action sequences are basic by 2018's standards, the film has aged like fine wine.

With Avengers: Infinity War just around the corner, and this being the 10th anniversary of Iron Man, here are 6 quick facts about the one that started it all. Because why not.

6. Tom Cruise Was Nearly Iron Man

Can you imagine Tom Cruise as Tony Stark/Iron Man? I can. And we would've all been the poorer for it (especially Robert Downey Jr.; like, literally). Around the late 90s, when Iron Man was still bouncing around in Development Hell, Cruise was offered the part. A certified action hero with a touch of Prom Queen Syndrome Tom Cruise may be, but something about his witless cockiness just rankles. His hubris undoubtedly helped to sink Universal's laughable Dark Universe. Marvel dodged a bullet here.

5. It Was Mostly Improvised

There was a vague outline of a script, but much of the dialogue in Iron Man was improvised. Actors would arrive on set with barely an idea of what they were going to say. Jeff Bridges, who played Stark's adversary Obidiah Stane, described the experience as a "200 million dollar student film". This goes a ways to explaining Iron Man's naturalistic feel. But in this writer's opinion, this approach went sideways in Iron Man 2. Just rewatch it with the knowledge that it's mostly improv; it's a lot actors babbling over each other and scenes dragging on. Iron Man, though, struck the right balance.

4. Phil Coulson's Part Was Beefed Up

Remember SHIELD Agent Phil Coulson? In the first few Marvel flicks, he was the connective tissue. This affable, competent G-man befriended all the Avengers before, well, The Avengers. However, his part in Iron Man was originally much smaller. But actor Clark Gregg had such great chemistry with the cast that it was decided he should have more to do. The universe building here happened organically. Take notes, DC/Warner Bros.

3. Paul Bettany Had No Idea What The Film Was About

Despite playing Tony Stark's AI helper JARVIS (Just A Rather Very Intelligent System), actor Paul Bettany had no idea what the Iron Man films were about. He'd just show up, record his dialogue for two hours, and then leave with sacks full of money. The actor joked that this made him feel like a pirate. But since Bettany now portrays Vision, he's got way more to do and most likely gets paid a similar amount of money for it. What a gip.

2. "Iron Man" Was A Huge Gamble For Marvel

In the 1990s, Marvel declared bankruptcy. So dire were their straits that they were forced to sell the rights of many of their popular characters to various film studios (which is probably why, at least for now, you're not going to see the Fantastic Four and the Avengers play poker). Although Raimi's Spider-Man and Bryan Singer's X-Men were making money hand over fist when the modern superhero craze began, Marvel saw none of the profits. So in 2005, Marvel struck a half billon dollar deal in which they would get to produce movies about the few characters they still held exclusive rights to. The collateral for this 500 million dollar loan? Every character they owned. If Iron Man wasn't the hit it was, Marvel would've immediately lost all exclusive rights to Captain America, Thor, Hawkeye, and the rest.

1. Favreau Fought Tooth & Nail To Get Downey Jr. The Part

Although Robert Downey Jr. was regarded as a great actor before Iron Man, in Hollywood pre-2008, he was something of a pariah in the industry, with a troubled history of drug use and being a menace. Because of his ruined rep, Marvel were naturally fearful of casting Downey Jr. They shot down Favreau's suggestion to cast Robert Downey Jr. multiple times. But Jon Favreau saw parallels to the fictional playboy billionaire and Downey Jr's real life, and knew that he'd be perfect for the part. Of course, he was right.