Based on the unreleased dungeon crawler game, and I'm making an AU about it >:)

The basics of the AU are that it takes place in a fantasy-themed Neighborville that the False Lord Zomboss already zombified. This phenomenon caused all residents to evacuate to an isolated area with a fair amount of resources and zombie-free. However, unlike their old homeland, resources became harder to maintain each month because of their different production and living methods. It could be the end of humanity until a courageous peashooter stands up for his citizens to travel far and wide for help & take back Neighborville from the zombies. But he needs a guild as he cannot do this alone, so the current land selects the greatest heroes to join him in the adventure.

Meanwhile, at Neighborville, a prophecy was given to False Lord Zomboss. It said the plants traveled to build an army from different regions to perform a crusade against his kingdom. Not wanting to start another war, False Lord Zomboss sends out his best warriors to stop the plants and maybe get information about the undiscovered regions for more brains.