Could you have a business in the U.S. which allows you to deposit money and make an investment in a share of stock and pick the outcome? Let me give an example.
I deposit money to the site and each dollar is represented as credits. Facebook stock is at $3/share. I decide to put up $3 for one share. I then choose if the stock will go up or down and the length of time. If I choose it goes up, and it indeed goes up, I win say 70% credits, and if it loses, I lost 85% of my credits toward that share. People could then cash out afterward.
So, would this be legal, or is it online gambling? I live in California. This system would be used online.
You could not do it without a securities license and no one would "play" your game when there is a traded "options market" traded on exchanges around the world. In addition it would also be considered gambling, and the fact that you use credits or chips or matchsticks while the game is being played changes nothing.
The above is general legal and business analysis. It is not "legal advise" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.