Agents of BIFROST
It started with a punch. And then a bite. And then the end of the world.
This Earth has several differences that point to a Divergence in the mid 80’s.
Steve Rogers, known here as Colonel America, has served a half-term as President of the United States, with James Buchanan Barnes as his Vice President. This is most likely due to both Steve and Bucky going into the ice together, and therefore Bucky never becoming the Winter Soldier. Being awakened together, and both joining the Avengers, caused a shift in the standard world timeline that spiralled out from there.
Certain world-changing events seem to have been delayed or avoided altogether, such as the Dark Phoenix event, the Clone Saga, and the Secret Wars. Team membership seems to be the same as during the 1980s of Earth-617. Additionally, for what appears to be sheer random reasons, master thief and occasional anti-hero Black Cat has a twin sister, known as White Cat. Adrian Toomes (the Vulture) sided with the heroes and never became a villain in this world. He has allied with Spider-Man several times, assisting in the defeat of many animal-themed villains, such as Rhino, Doctor Octopus, and Puma. Galactus (and by extension, Silver Surfer) have never taken an interest in this Earth, and as such the Fantastic Four have a less public presence. Other Alien beings have also interacted with this world to a much less extent and as such SWORD is not a stand-alone organisation, but is a division of SHIELD.
The most recent change to the timeline that caused the divergences of this world occurred less than 6 months ago, when an alternate version of Robert Reynolds, known as The Sentry punched his way through the dimensional barrier along with Ashley J. Williams. The Avengers arrived on the scene to find someone they didn’t recognise who held incredible superhuman power. Seeking to aid the newcomer they let down their guard and that is all it took. The Sentry overpowered them all and managed to bite them. This was the start of the Zombie infection. Six months later, humanity is nearly gone. Small pockets of living beings are making an ill-fated “last stand” against super-powered Zombies.
May the Gods of the Multiverse have mercy on your souls….