Roleplaying with only one page of rules?
Well, yes and no.
There is a roleplaying system available online, a pencil and paper system as downloadable PDF files and with a print-on-demand option, called the 1PG system. For the purpose of playing a game all the rules and information a player needs is on the one page of character sheet and rules combined. Most of the genre books are about 13 pages which includes additional rules specific to the genre and usually 5 or 6 scenarios/adventures.
Rules lawyers and roleplaying geeks will be shocked, shocked I tell you, about the suggestion of playing a system with such brevity in its rules. For the rest of us who aren't into spending 2 and 3 hours generating a character just so some gamemaster with self-esteem and pathological ego issues can kill them off in 5 minutes and act like it was nothing, to them, this does provide a very useful system for pick-up games.
A group of friends I used to game with several years ago would have made good use of this. We were not specifically a gaming group, just a group of friends who got together and watched movies or played games, usually board games, and often both activities. We occasionally got together for roleplaying, but the problem was that we would have to set aside the entire time for a roleplaying session as it was time consuming.
It is not like we did not have the desire to play a roleplaying game, and sometimes we tried a pick-up game after watching a movie, particularly if the subject of the movie we had just watched fit with the game as it had us in the mood, but by the time everyone had their characters generated and just starting, then someone would have to leave, then another, and it would end shortly after that.
A system like the 1PG system can have characters generated within a matter of minutes, and I do mean minutes unlike so many roleplaying games that claimed the same thing before and those minutes turned into 60 or more minutes. And being that each genre book comes with its own adventures, each also only taking up one page, a group of players can have characters generated and be ready to go with a playable game within 5 minutes.
Pick-up games can be fun, but usually are not doable with most RPG systems. Not only is the 1PG system ideal for pick-up games, it also has several genre books, each a complete game and not requiring a core set of rules as there is no core set of rules; the basic rules are in each genre book. Something like this would have been ideal for the group I met with as many of the genre books fit with popular subjects such as modern horror, pirates, westerns, sci-fi, disasters, spies, and even more, including some fan-made genre books you can find online, all of which fit with popular movie subjects and can turn a movie night into a movie and roleplaying night.
With it being available as downloadable PDF files you can print out character sheets on your computer printer, and all it uses, mostly uses, is one six-sided die (1D6) which you can pull out of any old Monopoly game rotting away on the shelf.
The above is not an affiliate link nor do I make anything by linking to them. I just like the game system and am a fan of Precis Intermedia and some of the games they publish. 1PG is actually owned by another company but is carried by Precis.