Our university will have some Open Days for prospective students over summer, and our gaming society wants to present itself. Any somewhat traditional way of playing an RPG will take too much of visitor's time, and if we want to reach more than a selected few people, also more GMs and table space than available.
I am therefore looking for alternative ways of giving what will essentially be passer-bys a bit of role playing experience if they are interested.
What techniques facilitate me to allow someone to join playing this game for anything up from five minutes and does not create too much overhead even if someone decides that it's not to their taste before they even got into it properly?
I believe I have at some point read that presenting games at trade fairs might be done in a fast drop-in-drop-out style (or in very short slots, but a fixed commitment of 15 minutes expected might already be too much for someone who is just casually looking around all university societies), what do I need to do to have something like this run smoothly, and which game is best suited for it?
I know that I will have to run it in a very rules-light system (considering Roll for Shoes or Risus, but I'm by no way restricted to a particular system), so that I have to explain barely anything when a new player drops in. On the other hand, I have no good idea on how to enable a newly dropped-in player to have a rough idea of the plot (no matter if serious-linear or emergent-silly), so that they can immerse and get going immediately.
Insights from experience with running a game in a situation similar to the constraints given here are appreciated. (Did you have a way to deal with lines and veils? Did handouts help or hinder? Very linear plot with a big countdown, or no prepared plot at all?)