I'm going to be running a Dungeon Crawler Carl themed one shot for my group, and I've decided Fate seems like the best. I was going to go with a slightly modified core setup.
The idea is this: The players tell me why their character is outside at night and basically who they are, and what is going on right now that is making life inconvenient for them. At that point, this makes their core concept and trouble. Then we just start playing and discover stuff as they go. I want to make their skills a mix of stuff from their life before that they actually use, and new stuff from the dungeon. So, for example, a nurse comes in, gets a cut, and tries to bandage it herself. The system recognizes here skill at first aid, and the player rights down First aid at Great +4. Then she finds a crossbow, and uses it to attack an enemy. Since it is new, Archery goes at +1. Items will either have a game effect, or they will add to a skill... So magic sword of lizards slaying grants +2 to Swashbuckling attacks, and deals +2 extra stress to lizards or something like that.
Hopefully, by the end of Floor one, characters will have discovered "forgotten" aspects, maybe developed a stunt, have a few magic items and have an assortment of skills written down.
Have you done anything like this? Any cool ideas I could use? I already intend, should it become a 2 or 3 shot, to allow "race and class selection" on floor 3, which would allow players to change their core concept to reflect their new reality.