Only an idiot has no marketing strategies worked out before the completion of the title.
If you are making a commercial game, this is very true, if not-so-diplomatically said.
Reminds me, about a year ago I sat on a plane next to guy who talked my ear off about some software product he was going to start selling. Very enthusiastic and got me engaged.
So, I asked: "Who's your target market?"
He replied: "The consumer."
I politely half-listened for another five minutes, wished him luck, and then made motions towards my laptop...