Deal Or No Deal
This game is the online version of the this popular TV game show.
The concept is very simple: you choose one suitcase with an unknown amount of money in it and start revealing and eliminating other money suitcases.
Every once in a while the banker will offer you a sum of money for your suitcase (based on the sums of money that haven't been revealed yet) and you need to decide whether you want to keep your suitcase or take the money.
At the end you either end up with a large sum of money (fake money in this case but on the TV show it's real money) that you either took from the banker or a few bucks that you have in your suitcase (or lots of money that you happened to grab in your suitcase).
It's simpler than it sounds, check it out...
I got $350,000, how bout you?
Play the game
If you like this game then check out this variation on the original game: Meal or No Meal. Same concept except you're playing for a meal.