For brokers the stock market is their life. They understand the trends and when to invest. The free online stock market games I have listed below, are educational and some offer free prizes for winning portfolios.
Virtual Trader is a stock market simulation of the UK market. With your registration you'll get 100,000 pounds (UK currency). Once your registration is complete, you will have your choice of companies to invest in that are listed on the London Stock Exchange.
A free online stock market game based on the UK stock market. There are no prizes, only educational gain, and a chance to try your luck without losing money.
This is the perfect introduction to the stock market for gamers! You get to trade stocks of games, something young gamers may understand more than about getting in early on some unknown company. "The simExchange" is completely free and online. To start playing you only need to create an account. After that you can buy, sell, and check on stocks wherever you can get online.