A while back, in the midst of remembering Ivan Reitman, I wrote a little about rule conversion that hinted at the possibility of using 5E D&D as the base for a game intended to be about as streamlined as the old Ghostbusters RPG. You could create a character pretty much the same way in either system just by determining attributes/traits and adding on some proficiencies/talents. If it works for a pickup game of Ghostbusters, it should work for a pickup game using 5E rules, eh?
For the adventure, I modified and quickly converted the Call of Cthulhu convention module Dead Boarder to take place at Miskatonic Community College on Halloween 1985. (Note: I definitely recommend this scenario, as it's a pretty cool and easily adaptable Lovecraftian romp, and its convention-game focus helped us keep a one-shot as an actual one-shot, which we sometimes have trouble with...!) And honestly, I think it went pretty darn well. Background-only 5E gaming may just become a go-to for themed one-shots I want to try out.
I mean, when players come to the game with characters like the one below, how can things go wrong? Quick creation...just enough substance to care about the character through a single session...defaulting to 5E rules that we all know reasonably well...I realize there's nothing groundbreaking to this approach, but I was really pleased with the outcome. Here's Rachel's character, sharing without her knowledge or permission or anything like that but I really don't think she'll have an issue with it...
40s or 50s, tall and slight but with ropey muscles, thinning brown hair and clean shaven. Wearing classic olive-beige jumpsuit of a custodial worker.
Str 10, Dex 12, Con 10, Int 14, Wis 9, Cha 14
Skill proficiencies: Repair, Perception
Tool proficiency: Cleaning equipment (floor buffer, wet vac, etc.)
Languages: English, Spanish
Background Feature: Knows Where the Bodies are Buried - For the campus where Milt works, he knows where every employee (staff and faculty) keeps their files and important papers and can access them at any time (licitly or otherwise).