Here's an edited version that I've found on the HERO message boards (by Shaft) with the elements covering Superman's part in the universe:
- 1912 - Brainiac realises that Galactus will destroy Krypton- he begins collecting the planet's accumulated knowledge to ensure its (his) survival.
- 1914 - Galactus destroys Krypton. Kal-El is sent to Earth in a rocket ship. Brainiac escapes the exploding planet with the collected data.
- 1920 - Kal-El found by Martha and Johnathan Kent
- 1929 - Every once in a while, Superboy is spotted in Smallville, KS.
- 1938 - Superman makes his first appearance in Metropolis.
- 1942 The Invaders and the All-Star Squadron are formed by the numerous superheroes that join the war effort.
- 1946 - Superman reveals his identity to Lois Lane. They marry, but are unable to have children.
- 1953 - The JSA's actions in the Korean War help bring about an armistice.
- 1960 - The Silver Age heroes shy away from joining the JSA, which is perceived as an war veterans superclub. As the JSA members start retiring, Superman, Batman, Flash, Green Lantern, Martian Manhunter, Wonder Woman, Hawkgirl II and Aquaman team up to fend off an alien invasion and decide to stick together as the Justice League. Aquaman declines the invitation, and Batman opts to only work part time (though he provdies funding) but the rest of the team stick together. Some of the JSAers who are still fit for battle come aboard too.
- 1963 - An assassination on President Kennedy by Doomsday is foiled by Superman, but the world is shocked as Doomsday beats the Man of Steel to death on live television after a battle that rages halfway across the US. Despite Superman's return a few months later, decades later people still remember where they were when they heard that Superman was dead.
- 1972 - Lois Lane dies. With his parents dead many years earlier, Superman retires his Clark Kent identity and works as Superman full time - beginning the disconnect he will start to feel with mere mortals.
- 1996 - Magog kills the Joker after he wipes out the staff of the Daily Planet. Superman brings in Magog for murder, but Magog is acquitted. Superman goes into seclusion.
- 2001 - Magog leads a team of super powered vigilantes to bring in the Absorbing Man, who uses Parasite's powers to augment his own and mimic the traits of a nuclear reactor before setting his sights on Captain Atom. He loses control of his power and explodes in a nuclear blaze, destroying a large part of Kansas. Outrage results in the passing of a superhuman registration act. Steve Rogers is arrested when he refuses to bring in heroes that choose not to register. His imprisonment is viewed as unlawful and inspires a large number of heroes to stay underground. These underground heroes, the "Outsiders", are led by the Batman (who immerses himself into the role full time after his identity becomes exposed) & Luke Cage. The Justice League struggles as many of their members side with Batman. The Avengers are less torn since they've always been government agents since day one. Wonder Woman pulls Superman out of retirement to rally the pro-registration side, which Superman leads, with a heavy heart.
- 2001 - A Superhuman prison is built in Kansas to contain the villains and unregistered vigilantes. Batman gets a team into the facility where Steve Rogers is being held to rescue him, but Rogers chooses to stay in prison and fight the system from within.
- 2001 - As the nation is distracted by the Superhuman Civil War, 15 jets are hijacked for use as weapons by suicide bombers working with supervillains, including three military planes carrying nuclear weapons. 12 of them are stopped (the nukes are stopped by Superman who ends up comatose after the ordeal).
- 2001 - In the aftermath, the heroes realize that they still have to band together. Officially, registration remains, but failure to register is a misdemeanor until compounded with a violent crime, so the pursuit of unregistered heroes is low on the priority scale. Steve Rogers is released from prison, but quickly realizes that he can be more effective on the political stage than as a costumed crimefighter.
- 2002 - Wonder Woman gives birth to Superman's child.
- 2004 - Red Robin, Starfire, Cyborg, Changeling and Nightwing II are the mentors to the third generation of Titans: Superboy II, Wondergirl II, Impulse, and Nightstar (Dick Grayson & Starfire's daughter).
- the strong influence of the now-classic Elseworlds-or-is-it storyline Kingdom Come. It was much like the Civil War storyline that later came out in Marvel, except for the fact that humans became another side in the war between two sides of the superhuman world;
- the questions raised about Krypton and the many other alien races out there in the DC and Marvel Universes -- the Kree inclusion is an interesting one;
- the impact that having Superman (and the other heroes) would have on historical events is significant, and successes or failures in stopping things like assassinations and wars and terrorist attacks would likewise impact the character itself.
- interactions between Superman and Captain America, as the classic flag-waving characters of either universe, would be particularly fiery during the Superhuman Civil War.
The next timeline comes from www.writeups.org, with a slightly different take on things:
The planet Krypton explodes, killing most of the inhabitants. Scientist Jor-El manages to save his infant son Kal-El by sending him in a rocket to Earth. Two cities, protected by atmospheric domes, survive: Argo City, a peaceful scientific colony; and Kree-Lar, a military outpost. The two clash over the division of resources, and a long civil war begins.
Kal-El, a.k.a. Superman I, makes his public debut.
The Kree discover Kal-El's presence on Earth, and send a scout ship to capture him. But a malfunction in the ship causes it to explode in Earth's upper atmosphere. Two escape pods survive the destruction and land at different locations. A mortally wounded Mar-Vell lands near Fawcett City and staggers into an abandoned subway tunnel. There he meets the ancient Egyptian wizard, Shazam, who saves Mar-Vell's life by placing him in stasis in the other-dimensional Negative Zone. Shazam then gives a pair of mystical bracelets to a young orphan named Billy Batson. The bracelets allow Billy to trade places with Mar-Vell for a few hours at a time. Americanizing his name to Captain Marvel I, the Kree warrior becomes a powerful force for good on his adopted planet. Yon-Rogg, meanwhile, lands in Germany, where he forges an alliance with Adolph Hitler and takes on the new name of Captain Nazi.
In the wake of Pearl Harbor, the Justice Society attempts to invade Japan. Unfortunately, a young prodigy named Victor Von Doom uses a mind-control device to prevent the most powerful members from entering the Axis territories.
With the JSA unable to enter the war effort, British Prime Minister Winston Chruchill suggests forming a second team to fight in Europe. Captain America I, Bucky I, Human Torch I, Toro, and Sub-Mariner answer the call as The Invaders. Later in the war they are joined by such stalwarts as Black Condor, Doll Man, the Human Bomb, the Ray, and Phantom Lady.
Superman I and Lois Lane are wed, and their son Superboy is born nine months later.
In response to accusations from Senator Joseph McCarthy's House Un-American Activities Committee, the Justice Society disbands. The chief witness against them is Captain America III, a man recruited by the government to assume the role.
Superboy travels to the 30th century to join the Legion of Super-Heroes. Though he spends several years there, he returns only a few moments after he left. Now an adult, he adopts the name Superman II.
The Kree attack and destroy Argo City. The only survivor is Kara Zor-El, who escapes to Earth and meets her cousins, Superman I and Superman II. Inspired by them, she takes on the identity of Supergirl. Superman I arranges for Kara to be adopted by his friends Fred and Mary Danvers, and she becomes "big sister" to their young daughter Carol.
Superman II, Batman II, Flash II, Wonder Woman I, Green Lantern II, Aquaman, and the Martian Manhunter gather together to form The Justice League of America.
While suffering from amnesia, Superman II meets and falls in love with Sally Selwyn. When his memory returns, he reveals his true identity to her, and the two are wed. Before long, they have a son, Clark Kent III.
Galactus makes his first attempt to consume the Earth. He is thwarted by the Fantastic Four and his own rebellious herald, the Silver Surfer, who is exiled to Earth as a result.
Darkseid, evil lord of Apokalips, takes an active interest in Earth. His schemes are opposed by the heroes of New Genesis: Mr. Miracle, the New Gods, and the Forever People, as well as Jimmy Olsen Jr. and his allies The Teen Brigade.
Against their fathers' wishes, grade-schoolers Clark Kent III and Bruce Grayson take on the identities of Superman Jr. and Batman Jr., respectively.
Superman II's daughter Kara, a.k.a. Power Girl, makes her superhero debut.
A mysterious being called The Monitor from Beyond gathers the villains of Earth into a massive army to conquer the universe. In return, he grantsthem increased power and renewed youth. Earth's heroes attack and eventually defeat this army, and many of the older heroes sacrifice their lives in order to destroy The Monitor.
After reviewing this, my approach would consist of the following guidelines:
- review the published cross-overs to see what they have to say about things;
- review the alternate timelines and Earths to see what they have to say about things;
- follow the generational approach as a primary philosophy -- to give the Supermen and Superwomen of the different eras a chance to shine and to retire (or go out in a blaze of glory);
- establish their role in key comics events like the Kingdom Come / Civil War saga, the Crisis on Infinite Earths, the coming of Galactus, the Kree-Skrull War, and so on.
- establish the ongoing role in the current gaming universe: perhaps one where the Super-Family isn't quite so dominant that they can swoop in to save the day when the PCs are in a jam.
- Figure out what effect natural friends and rivals might have on the history. Case in point: Kingdom Come / Civil War -- what would Batman or Captain America or Shazam or Captain Mar-vell or Wonder Woman do?