The Big Deal is an investing game from Hargreaves Lansdown. It's free to register. You start the game with £100,000 (only virtual, unfortunately). You then choose which stocks or funds to buy. Registered players are then placed in a league. There are monthly prizes of £1000 for the five players who perform the best each month. There's also a prize of £10,000 for the overall winner whose investments have made the most money when the game winds up on the 30th of May, 2014.
The game begins on January 14, 2014.