I wrote this idea after seeing The Purge: Election Year:
It'd be a crossover of Resident Evil and The Purge. Selectively, I'd use certain mythos and combine them. The idea is that the events of Resident Evil 0 and Resident Evil happened. Afterwards, Umbrella covered it up, and managed to clean things up before the Raccoon City incident happened in this timeline. Cut to a couple years later, and the New Founding Fathers are in power, and The Purge is a thing. The NFF still keep an eye on the world and there's still potential for wars, and everything else. They want new weapons, and Umbrella has been continuing their worker.
Albert Wesker steps in with an idea. As most Purging stays within the cities and towns, they plan to set up blocks around Raccoon City, shoot anyone leaving on site. And, as everyone is Purging, Umbrella drops several BOWs (aka Biological Organic Weapons) into the city as a weapons tests.
21 Jump Street film series + Men in Black + Original Ghostbusters + New Ghostbusters.
Minus Jump Street, I always considered this as an actually interesting idea. I mean, the GBs could exist in a world where aliens existed, but with the MiB, no one knows. Eventually, someone with the knowledge in the government, maybe an alien senator, decides after the paranormal threats seem to have died down, humanity would be better off not living in fear of the paranormal, so the MiB was asked to stage a mass neuralization, with some exceptions. Egon and Ray stayed in case a future threat arose. Ray took up jobs as a cab driver, to stay close to the city he loved while Egon continued experiments with the leftover equipment stored in a safe room built beneath the firehouse. Venkman, after telling Ray he'd see him on the other side, took a little too well to the neuralization, and came out the other side as skeptic Martin Heiss. Winston meanwhile fell back on skills he learned Ghostbusting, but couldn't remember when he'd learned it, and opened a funeral home.
Fast forward to 2016. Egon has passed away, and Ray has become jaded and pretty well stopped his work, driving the cab full time. Then GB2016 happens. That is why the government has inside knowledge on the thing that have happened. That's also why things sort of fall into place as they do, such as the girls wanting the firehouse for some reason, the guy in the subway painting a no-ghost logo, etc.
And besides, what I'd really want to see is the Enterprise crew on the Pred homeworld anyway, where they wouldn't have the tech advantage as much.
