Instant Game (2007)

From the introduction:

What is Instant Game? Instant Game is a tool for creating and playing new RPG settings on the spot. With the Instant Game charts and our flexible Instant Game rules set, you can roll up a completely original setting and plot, create and develop characters “on the fly,” and be ready to roleplay in just a matter of minutes. We know that seems incredible on its surface, but it is also a wonderfully real possibility. Instant Game is painless, as well as being some of the most exciting and challenging gaming you’ll find

How does it work? The steps to creating an Instant Game are simple:
1) The Gamemaster (GM) rolls on the Instant Charts provided to get Instant Setting rolls and Instant Plot rolls.
2) The GM (usually with help from the other players) then puts the Instant Setting elements together to create a coherent
world.
3) The GM assembles the Instant Plot elements into a workable storyline.
4) The GM explains the setting and any needed character guidelines to the players.
5) The players create Instant Characters based on our simple character creation rules.
6) Then play.
We’re not kidding about this. Get your gaming group together with no preparation whatsoever ahead of time. Throw some dice, consult our Instant Tables, and in 30 minutes or so, you can have a complete and novel roleplaying setting ready to roll, with a plot and characters and everything. It’s surprisingly a lot simpler than you think.

Instant Game is available as a free download from the publisher's site.