If the real money games also paid off that big, the casinos would quickly go bankrupt. Although it can't be confirmed, trying out the 'play for fun' versions at several online casinos often results in hefty imaginary bank accounts. There is a difference in the odds between the 'play for fun' version and the real money versions of online games. Of course, these games don't pay out any real money. Players can try out the games for free using a play account filled with a few thousand dollars.

Some sites only offer a download-to-play option. Players can also download the casino's software and play the games in a separate application. Many online casinos offer 'instant play' versions of their games, which usually run within a Web browser using Java. The sites offer their own odds, which in some cases are better than the odds offered by the traditional Las Vegas bookmakers (due, in part, to the lower overhead required to run an online betting site). These sites allow users to place bets on athletic competitions of every kind, as well as other events like political races or the outcomes of reality TV shows. There are also sites that offer online sports betting, which is another form of gambling.