Most contests are won by people who over leverage. They may win a contest that lasts a month but see what their performance is like over a couple of years. Most use demo accounts as well so also not a true reflection.
Best option is to trade and play a game with yourself. The game is if you can follow your trade plan or not, sounds easy but one of the hardest games around to conquer!
It always great to play games and contests as best results are achieved in competition. But try to choose games which doesn't involve money such as demo contests. Here is what I found from one of my brokers http://bit.ly/1wZ2SB3 never bothered with it as real trading appeals more to me but you can try, it's risk free.
The best forex game around is to actually play the real markets with real but minimum stake money. e,g, 1 penny stake on a free platform like MT4/5
Wait 'til you are consistently profitable and only THEN increase your stake gradually.
Keep you amused and frustrated for years. Great for retirement but don't expect to make zillions straight off.