While I understand that it might be a bit easier if there was a set story to follow, I would like to experiment with a free-form game
Just to inform you, freeform doesn't have anything to do with the presence or absence of a set story.
In Freeform games, characters don't have stats behind them, and if anyone tries anything, it's up to themselves if the action succeeds or not.
In contrast, characters in System games are backed up by several statistics that also determine the chance of a certain action succeeding, usually involving some dice as the random factor.
Both Freeform and System can have a preset story, or be completely open to the players.
Just thought I'd inform you. Sorry for the hijacking.