I have an idea for a game. How about trying to run a car company? You have several sets to tackle: advertising, R&D, finance, unions and dealers. Many years ago, I used to play a car design game in DOS and there have been some car company games but I can’t think of a recent game. It could be like SimCity except for a car company.
That game would be nice and would fit for business minded individuals… And in fact, it will also be a huge game for young professionals that are into formal games 
The game could expand for decades from the start - start off in the 1950’s and reach into the 21st century. Maybe the player can start a car company from scratch and struggle against competitors to gain market share and profit. Perhaps there could be a chart showing the stock price of company based on decisions made by the player. Throw in real world challenges such as health care costs and macroeconomic conditions such as oil crises and recessions. Keep the shareholders happy or they’ll call for your dismissal!
There was a car sim game a few years ago, an isometric tycoon style thing, but I don’t recall it being especially good. Still, it’s out there somewhere.
i think there is already a few such online games out there, do you mean one based on a sport like Rally or F-1?