Start with a quick discussion about the plot & setting of the game, but keep it simple: use a trope (zombie apocalypse, mega-quake, alien invasion) that everyone is familiar with and a location that is either generic (shopping mall, ski resort, subway network) or, if specific, one that everybody knows and recognises (your home town, Disneyland, the Vatican.) If one player wants to be the GM, they can sketch out a plot beforehand and reveal what's going on through play, but they shouldn't be married to their ideas.
Write out some locations on medium sized pieces of paper, at least one per player, all of which should be part of the setting, e.g. if your game is set at a ski resort, then locations might be the lodge, the ski shop, the cable car, etc. Now everyone takes 4-6 small pieces of paper and writes a brief description of a character on them: you just want a name, an occupation and any relationship they have to any other characters. Decide how many characters each player will control, so that everyone has the same number; as you create these, place them at the locations they begin the story at and place a coin on each one.
To begin the game, everyone chooses one of the locations on the table and narrates what is going on there before whatever event is going to take place does so; as soon as this is done, the event takes place, as decided and described by the players or the GM. From here on in, the agenda for each character is to survive, but the agenda for each player is to have at least one of their characters be a bad-ass hero!
There are two ways in which tension and drama can be injected into the game: you can decide to have your character try something or another player can narrate a situation that your character has to respond to. If there is a GM in your game, then they are responsible for the latter, but you are always responsible for the actions of your characters. Whenever a character attempts to do anything non-trivial (that is, above the level of danger and complexity associated with tying their shoelaces) there are four levels of response:
Deadly: the character dies. This level of response is always the player's choice and it overrides the next three levels, but if there are several characters all co-operating on the same thing, then the rest of them automatically succeed if one character takes this option. Any other 'big task' the character was attempting (piloting their fighter jet into the vulnerable spot on the alien mothership...) will also succeed automatically if the level of response is deadly.
Risky: this is a 'succeed or die' situation; if the character fails, they're dead. For example, trying to swing on a rope across a river of molten lava is risky.
Tricky: a test of skill where failure can place you in danger; if the character fails, the level escalates to risky. For example, driving down an icy road is tricky.
Elementary: a test of skill that relies on an area of the character's expertise; if they fail, the level does not escalate. For example, adapting the power cables to a new purpose is elementary for an electrician but tricky for anyone else.
When you choose to have a character do something, it's usually tricky, unless they have the right skills & background to make it elementary; when your character is forced to react to a situation, it's often because it's risky, but you can make it deadly if you want to. For any action which is not deadly, you toss a coin to determine the result:
- Heads: you succeed! Well done, have a cookie.
- Tails: you fail! Bad things may now happen.
Characters will die but their legacy lives on: when one of your characters dies, place their coin on another character you control; as long as a character has more than one coin, they can't die. When you toss a coin, you can opt to spend it if you fail and that task becomes a success instead; in essence, you can treat everything they do as if it was deadly, so you can opt to lose a coin to earn an automatic success for whatever group of characters they are in. Coins spent in this way are removed from play, only the last coin a character has gets passed onto a new character when they die; if your last character dies, pass their coin to another player and buy one of their characters off them, but they choose which character you get and which of their characters gets the coin.
If one character decides to attack another character in any way, placing them in danger, then the attacking character first makes a risky test; if that succeeds, the defending character then has to make a risky test. If either test fails, the other character gets that character's coin.
The game ends when the story does, such as when the threat is overcome or escaped from or when there are no surviving characters.