I just wrote a game. It's my first ever game! I think you should try it too, especially if you haven't written a game.
Open a text editor. Write for a minute. Think for a minute. Revise for a minute. Post what you produce. Play what you produce! Tell us how it goes.
Here is mine, with thanks to Jason Morningstar, Graham Walmsley, Luke Crane, John Harper, and Vincent Baker.
For three to four players.
Whenever you do something, you do it. If someone thinks maybe you can't do it, you have to prove that motherfucker wrong. With only a six-sided die.
Roll it. On a 1, it goes horrendously wrong. Look at the person to your left (the sinister direction). Ask them how it goes horrendously wrong.
On a 6, it goes horrendously right. Seriously, horrendously. As in, you were not expecting it to go that well. Look at the person to your right (the righteous direction). Ask them how it goes horrendously right.
Anything in between is up to you. A 2 is worse than a 5, that's all I'm going to say.
Practice good scene framing, if you know how. You've played GMless games before, right? No?
Okay, then in the beginning you nominate someone to go first. That person decides whether to set the scene or let it be set. If the active player wants someone else to set the scene, they just have to point at someone and say "You. Tell me what the fuck is going on."
Say what's obvious. Just go with it. Take no more than five seconds to frame the scene. Describe how things are going in the scene until someone doubts you. Then roll for resolution (on the conflict level), and the player on your left becomes the active player. When play comes back around to you, start a new scene. If your last scene ended with an unacceptable cliffhanger, then go ahead and continue that scene. In general, try to start and end scenes in one turn.
There is no character generation or default setting. That will come in time, Padawan. By that I mean, just play the game to find out who you are and what you can do.