Bullet Points
Bullet Points is what can be considered the ultimate What If story in the greater Marvel multiverse -- specifically, "What could possibly go wrong by pulling a bullet 24 hours back in time?".
The answer is, "there are changes by the bucketload".
Simply put, instead of shooting Professor Abraham Erskine on the 9th of December in 1940, that Nazi spy shot him one day earlier.
Cut to an airport, 8th of December: just when Erskine is about to take a plane in order to test the Super Soldier serum, the spy shoots him, killing not only the prof., but also another soldier in the process: Benjamin Parker.
Since Erskine had the formula in his head instead of writing it down -- in order to prevent any spies from taking advantage of it - Captain America never came to be.
A discouraged Steve Rogers kept waiting and waiting until he was the sole man remaining in the hall. So, the army noticed such patriotism and thought it was worth something, despite Rogers' weak body. Then they unveiled plan B -- a robotic and then-rudimentary armor -- that could only be worn by someone as thin as Steve Rogers. That was given the in-universe Fan Nickname of "Iron Man".
There was a downside to that -- to prevent the armor from getting handled by the wrong hands, whoever was given the suit would also have to be linked to an electric device who worked as a sort-of-key for the armor. The device had to be installed within the user's heart. And the future Iron Man needed to be awake during the operation. Despite all of the crap to deal with, the patriotic Steve Rogers accepted anyway.
However, the bullet also made other changes, as you can tell with the cover gallery (sans the 5th cover, not included for both aesthetic and spoileriffic reasons) used as the page image.
Without a paternal figure such as Uncle Ben, Peter Parker became somewhat of an Expy of James Dean's character in Rebel Without a Cause, and was wandering a wasteland alongside other fellow bullies. Pity his 4x4 ran out of fuel, of all places, where a Gamma Bomb was also going to be tested.
Back to Steve Rogers. The American hero Iron Man needed a technician to work on his suit: said technician wasn't anybody else than, you guessed it, Reed Richards -- and as a result, he had to postpone his space travel. After gaining fame as the man who worked on such an amazing product of technology as Iron Man's suit, when Steve Rogers finally told Reed to focus on his own career, he finally accepted to travel alongside Johnny Storm, his sister Susan and Benjamin Grimm -- but his fame made him an easy target. A man sabotaged the shuttle by setting a bomb on it and as a result, the shuttle fell down -- with Richards as the sole survivor, and even then, at the cost of a missing eye. After donning an Eyepatch of Power and a lot of angst over the loss of his friends, Reed Took a Level in Badass when given the opportunity of disappearing from the face of the planet -- by working for S.H.I.E.L.D.
When the aforementioned Gamma Bomb went kaboom, every life form (excluding Parker, because... uh... yeah) that survived the explosion was studied by Professor Bruce Banner. Including a spider, that, take a wild guess, ended up biting him.
We won't spoil any more of this miniseries -- you only need to know that J. Michael Straczynski, famous for his run on Spidey, wrote it with a rather brilliant premise: "A bullet can spread lives as if they were balls on a pool."
See The Nail for this series' DC Universe counterpart and Powerless for a series that similarly turns the Marvel Universe on its head and as such, for example, in Italy got reprinted together with Bullet Points in a single book.
Let's add tropes now -- again, without spoilers of course.
- Alternate History: No Captain America and no Fantastic Four.
- Alternate Universe Reed Richards Is Awesome: Even more so than ever - the Trope Namer himself, Reed Richards, posing as Nick Fury. Reed Richards becomes the head of S.H.I.E.L.D.!
- Note also that while he's taking Nick Fury's place in this universe, he's still Reed Richards -- as a consequence, S.H.I.E.L.D operates less through "clandestine super-spy antics" and more through "building super-cool super science wonders". And it is awesome.
- Arc Words: many. Every issue has its Arc Words, courtesy of the narrator himself -- such as the opening quote for this page, "This is a bullet, and this is what it does", that also opens the first issue.
- The Atoner: Bruce Banner -- in this reality spared the gamma bomb explosion that would turn him into the Hulk -- devotes his life to finding a cure for Peter Parker's condition because he holds himself personally responsible for what happened and is riddled with guilt as a result. This ends up turning him into Spider-Man instead.
- Avengers Assemble: this happens when every superhero is asked to help in the struggle against Galactus.
- Berserk Button: sure, just keep picking on Parker! You will regret it!
- Also from Peter: "MMMMAAAAAAAAAAAAAAYYYYYYYYYYYYYYYY???"
- Big No: when Susan dies in Reed's arms.
- Bread, Eggs, Milk, Squick: one of the issues has the following Arc Words -- Time. Space. Flesh.
- Crosshair Aware: the cover of the first issue, as you can see above. Also, the very first panels of the same issue.
- Determinator: Hulk versus Galactus. Seriously.
- Dropped a Bridge on Him: Baron Mordo's death is only quickly mentioned.
- Elseworld: did you think that a Marvel Universe with Reed Richards posing as Nick Fury was the same one where Reed Richards Is Useless? Seriously?
- Eyepatch of Power: Reed Richards, naturally.
- For Want of a Nail: the whole basic premise.
- Godwin's Law: while not one of Mark Millar's works, this was pretty much inevitable when the story begins during World War II.
- Killed Off for Real: the casualties include doctor Erskine and Hitler, Steve Rogers, Peter Parker, Ben Grimm, Johnny and Susan Storm, and Baron Mordo.
- Mythology Gag: while far from giving Powerless a run for its money, this series has its moments. Such as May mentioning that if Ben had lived long enough to bring Peter up (and hopefully even longer), things would have been different.
- Oh Crap: "Meet Galactus, eater of worlds!"
- This Is Unforgivable!: the trope is the Heel Face Turn that makes Silver Surfer switch sides.
- Unstoppable Rage: guess who.
- Wolverine Claws: yet another artificial example of the trope, this time equipped by Stephen Strange, who decided to work for SHIELD instead of going to Tibet, thus never becoming Doctor Strange. As a result, Mordo had no rivals, but still, he wasn't pure-hearted enough to become a Sorcerer Supreme and therefore Dormammu kicked his ass.
- You Can't Fight Fate: the final issue has the Arc Words: "Absurd, pathetic, inevitable".