So, Casino Royale is my new game in development.  It's a casino heist game along the lines of Ocean's 11- a crew of criminals pulls off a major caper.  (Or doesn't.)  It uses Blackjack as a resolution mechanic.  Play is supposed to be highly Gamist of the Gamble variety- examining risks, placing bets accordingly, and determining when to use one's special abilities.

Given that blackjack innately favors the dealer, special abilities are key to victory.  Every character has a number of special abilities, along the lines of "I can win at ties when picking pockets" or the like- a card game bonus based on a narrative fictional action.  Players are supposed to guide the action towards doing what their characters are good at, and have the ability to determine what actions the heist should consist of.  So they should do that.

Originally, I was just going to play with Tim and my brother (who is a gamer, but not an 'indie' or 'story' gamer), but my Mom and Dad, who play boardgames with me occasionally both joined in.  (Probably because it uses playing cards, which are normal, and not funny dice.)

Dad dropped out pretty early- he was tired, under the weather, and did not get the game at all.  (He tried to choose the special ability "I can look at the dealer's hole card... whenever I want to!"  He gets an A for effort, I guess.)  Mom stuck it out, and came up with clever, thematic ideas (donning a construction worker disguise, rerouting traffic, and creating a roadblock to allow a hijacking of an armored truck.)

The game was technically incomplete, so we had to adlib a few things, but we had a good time- made characters, did the rundown (which is like the planning montage near the start of the film- this is where the players tell the dealer (GM) what the plan is, and the dealer tells them what potential extra complications there are), then the play, where players do stuff, and either succeed or fail based on the blackjack hands.

It's clear to me after playing that there is a dominant strategy- do a few rounds of initial prep scenes, during which few chips are on the line, which can earn free chips later if successful.  (This is also true to the source material, where the first half hour or so is legwork and prepwork).  But my players were impatient, and went right for the big conflicts- and failed.  Of course they did, the house always wins.  They hijacked the money, but were followed to the safehouse.  One guy got away scot free, the other two were on the run, facing a possible murder rap.  Good times.

It's abundantly clear that the play techniques need clarification and refining- Tim and I had a conversation where we were both a little confused:
Tim:  "Who gets to decide where the diamond is?"
Me:  "Well, I do."
Tim: "Ok"  (proceeds to try to not do cool things about the diamond, but doesn't say that.)

and then
Tim: "So who frames scenes."
Me:  "The players do, each round, when they say what they're doing."
Tim: "Wait, what?"

So, clearly there's some authority question here- how can you frame a scene about stealing the diamond, if I have final authority over where the diamond is located?  (My gut answer is "do a scene first where you try to find out where the diamond is," but it doesn't answer the larger authority question, so much.)

Willow,

Sounds interesting.  Point of clarification: are the players/characters competing against each other or working cooperatively against the house (GM)?

Also, I am surprised to hear that you initiated your parents into roleplaying with a work in progress.  But it also sounds like your mom jumped right in.  I would guess that having such a clear win/lose premise baked into the game helped her.  At the same time, I've had problems with some newbies who latch onto the term "game" and expect the whole thing to operate like a typical board game.  For them, I've had more success with less Gamist fare -- which better separates the two activities conceptually.

It's completely co-op between the players against the house/dealer.

Yeah, the presence of my parents was unexpected.  I was ready to play with just Tim and Jon, and then my Dad said he'd try it, then Mom sat down with us too.  They most certainly aren't roleplayers, but I think this was a fairly nonintimidating activity for them to try- no funny dice, no big character sheets, no map, minis, etc.  So it turns out Mom has some 'storygaming' potential.

I'd say you have to either surrender authority during framing OR
provide a resource economy which allows the players to "seize control" of something you're trying to protect OR
do some kind of "Yes, But" or "Yes, And" mechanic for the GM which allows him or her to establish complications if a player tries to frame a scene around something being GM-protected OR
allow some kind of "qualified victory" if the players frame a scene that "bypasses" the caper, so to speak--"yeah, you stole the diamond... and its FAKE."

There's really a ton of ways to apportion narrative authority; it sounds like you just need to find a cost for seizing control which the players will find prohibitive in most circumstances (which might make using the seize control function more of a flag for "yeah, let's wrap it up now").
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I trust you intend to change the name. The Flemming estate has some high-priced lawyers, I hear....