Here's how game pitches should start:
1. GM Dreams it up
The GM comes up with the concept for the game. The GM then distills this into a very descriptive, evocative game pitch. A game pitch that has no wizards in it, for instance, maybe about pirates (see the link above).
2. GM Pitches the Game
Next, the GM emails the pitch out or tells the players about it.
3. Players Give Feedback
The players read/hear the pitch and give feedback. The GM listens carefully - not only noting what the players ask for and what they seem to like most; but also what they don't really respond to. Also, when players give feedback, the GM should assess whether it's feedback one player has, or whether the entire table agrees. "We don't want to play a game without wizards" says one player. The other players shrug. Maybe they were OK with a game without wizards. Maybe that one player wants to play a wizard. What's a good compromise?
4. GM Incorporates Feedback
The GM incorporates some of the feedback, to please the majority of the players. If the feedback is really negative, the GM goes "back to the drawing board." But once the GM has made changes - that's the game you're playing. You had your chance to give input. Note, the GM has to like the game they're running! No GM should change their campaign concept to one they don't enjoy. But the players also have to like it. If the players and GM can't agree, it's time to go back to the drawing board.
5. Players Make Characters
Now the players make characters appropriate for the game described in the (revised) pitch. Their character represents how they want to interact with the pitch. The players also create character hooks (aka backstory, ideals/bonds/flaws, background, known NPCs, and other sorts of things GMs ask for or players write unsolicited). Those hooks describe what stories they are interested in being involved in.
6. GM Creates Content for the Player Characters
Next, the GM builds some antagonists and settings (or revises and fleshes out the sketched ones he or she already made) based around the players' characters. E.g. if a PC is a Paladin, a holy order needs to be added. If a PC is looking for her lost husband, the NPC husband needs to be written into the setting, and the disappearance needs to be attributed to one of the antagonists.
7. The GM Starts the Adventure or Campaign
|Source: Wikimedia Commons|
You're a Paladin. Your holy order sends you on a mission to a ruined city to find out what mysterious force destroyed it. This woman (other PC) wants to tag along - says she's looking for clues to the whereabouts of her missing husband there. She's concerned he became mixed up in unlawful magicks. This mysterious man arranged it so he was assigned to help the Paladin investigate. The orders are clear: He will help investigate, and if he finds anything that looks like a book or scroll with strange glyphs, only he is allowed to touch it. He looks like a wizard. But no... that can't be. The wizarding traditions were purged by the holy order a thousand years ago...