Need a short RPG for beginners

After I told a relative of mine about me GMing a game of Mothership (sci-fi, horror based RPG, see r/mothershiprpg for details) for the first time, they became very interested and want me to run a game at a get-together for their friend group (we are both adults, but their friend group enjoys some lighter games like Mahjong or Trivial Pursuit, so it's not that out of character.) They said they don't want to spend their whole evening doing that, and asked if I could do it in less than an hour (that's more of a hard and fast rule, if it takes 90 minutes, I think they'll be fine with it.) I told them I would "think about it", because I didn't want to say "no" outright. But now I'm thinking, maybe it can be done? I would love to bring more people into the hobby.

Note: I can send people the rules beforehand (as well as answer questions and run them through character generation, etc.) That won't be a problem, the goal is, however, to spend as little of the precious time when everyone managed to get together in one place as possible.

I don't think I can run Mothership (or, god forbid, DnD) in that little time, but maybe there is some other game system that is good for short one-shots?