MMO gambling, when linked to currency with a real world value, is essentially the same as any other online gambling. The first major issue in the early years of MMO gambling was what constituted a tie to "real world value," as games with eBay economies were a gray area. Games such as SecondLife were much more clearly linked to real currency. Given that MMO games have the freedom to incorporate practically anything imaginable, they can have any of the types of online gambling integrated into the game, or to a lesser extent, acted out by players (i.e., player sponsored tournaments with a gold buy in and prize) without integration. So, like any other online gambling system, there were the perpetual issues of access by minors, taxation, and, of course, the endlessly murky waters of differing gambling regulations worldwide. Things took a rather abrupt turn with the passage of the Unlawful Internet Gambling Enforcement Act in the United States at the end of 2006.