In my many years of thinking about gaming (as opposed to actually gaming, but that's another rant) I have had a lot of ideas. Some good, some bad, some mind-bendingly awful. But several years ago, I had what may be the greatest idea in the history of man.
D&D - at the casino!
Okay, bear with me.
This is how it would work - the casino has its own sandbox setting, complete with wilderness and a megadungeon. Anyone who wants to play has to buy in - at, say, $100 an hour? It's hard to estimate how much to set this at without knowing how much gold the average PC is going to haul in.
So you pay your buy-in, and you send your character out to explore. Every gold piece you successfully bring back to town would be paid out as $1 in real life. And you can come back with the same character - starting out at 1st level your hauls might be meagre, and you might even lose money as you try to build up your guy. But as you get more powerful, you can take on stronger foes and haul in more loot - all at the increased risk of death, of course. And once that character is dead? It's gone unless you have a friend there who is willing to spend some of his winnings to raise you.
Of course the casino could fix such a game really easily - wandering encounter with Spectres on the first dungeon level! That's why this would have to be policed pretty strictly. Everything would have to be by the book, and all rolls would by necessity be in the open. Players would be able to call the DM on any ruling, and get a glimpse at the rules or notes to clarify what just happened. But as far as dungeon levels go, the official wandering monster charts would have to be adhered to, and set encounters would have to be reasonable to the dungeon level they are encountered on.
As for ruleset, it's tempting to go for 3rd Edition here, or even 4th - there's a lot to be said for the way they try to balance out monsters by Challenge Rating or experience point total. But this has to be a game that your average Joe Gambler might try out. So in the interests of simplicity and accessibility, it has to be Moldvay Basic/Cook Expert.
The only downside I see, besides bankrupting alegion of gamers, is that I would spend nearly all my time at the casino. But maybe, just maybe, I could then make a living out of playing D&D all day...