I had a recent role-playing-game experience that was really a knockout, and it came from dropping nearly all the rules.
I had a weekend where I was going to be gone on Saturday, while my 13-year-old daughter was hatching a plan to have some friends over to play "D&D" on Sunday. The kids don't really know what D&D is exactly, but they know they want to try it.
She needed a gamemaster who knew how to play, and tried to draft her 16-year-old brother, but it looked like a recipe for sibling sabotage. So she asked me, and I had absolutely nothing prepared.
(Well, I have a basic setting idea I'd been wanting to use, and you'll see how that plays out.)
But during the morning I had an idea. I was thinking about how most startup games get devoted to character generation, and it occurred to me -- what if we established all character abilities during play.
I applied to that a rule cribbed from Donjon, helped by me not having read the Donjon rules in a long time, so that I forgot most of how to use it.
So we ended up with just one mechanic: abilities defined as using some number of 6-sided dice, with rolls of 4+ treated as 'successes', and each success allows you to state a relevant fact of the world, Donjon-style.
Each player got 20 dice and started with one ability chosen. The setup was this: the characters start out in a giant canyon, waking up, with amnesia, knowing only one thing about themselves.
This idea came from my Catastrophe Canyon setting, which includes the idea that drinking canyon water causes various forms of amnesia.
After that, we started play, and most of the encounters they had derived from facts that they established through successes. It really worked rather well.
Each time they tried something, they could decide to assign from 1 to 6 dice to it, from their 20 total.
I'll probably want to post some more details later -- like the cake-monsters they fought because one player's successes 'found' some cake under a bush, and I turned that into a living cake with humanlike feet... but let me just say that this game session accomplished everything I'd hoped for.
One of the players had even played 'real' D&D before. I warned her in advance that what we were going to do wouldn't much resemble that, and she was game.