My children recently showed me an online game called Coffee Shop. The game can be found at a site called Cool Math Games.
In the game, you are giving seed money to buy supplies (coffee, cups, sugar, and milk). You then must come up with a recipe - strong or weak coffee, how much sugar, and how creamy. And finally, you set the price (but you soon learn that the price is set by supply and demand). You get feedback from customers and you adjust your price and recipe accordingly. The demand for coffee is affected by the temperture and, just like in real life, the temperture changes over the 14 days you operate the coffee stand. At the end of everyday you have to reorder supplies and adjust your recipe.
This is a wonderful game for teaching economics to children and it is appropriate for chidren of all ages.
There is also a similar game based on running a lemonade stand.