Just over a week ago, the long-anticipated MiniTycoon: Casino game hit the iTunes store, and it has already climbed to #1.

This free game from Social Gaming Network (SGN) works on Apple’s iPhone, iPod Touch and iPad devices, and brings realistic casino games to mobile users through a unique social interface.

Much like Zynga’s popular Farmville, the world of MiniTycoon Casino revolves around virtual currency. This currency, called Tycoins, can be purchased from the iTunes store (170 Tycoins costs $2.99). Tycoins are needed to create and maintain a virtual casino, and can be spent on slot machines, poker tables, and blackjack card games. Tycoins are also required to hire other users to act as dealers.

Tycoins can also be gambled. Players can win more Tycoins by gambling at other people’s casinos, and can earn Tycoins when other users lose them at their casino. The only catch is that Tycoins always remain virtual – they can never be exchanged for real money. This means that players spend and spend, but get nothing in return. SGN estimates the MiniTycoon: Casino will bring them $1 million in revenues per month.

Real money gambling apps do exist for the iPhone, but they cannot be downloaded from the iTunes store because of Apple’s anti-gambling policy. Instead, players must visit iPhone casinos to find them. Games like blackjack, slots, roulette, and other titles can be played for real money, and winnings may be cashed out, making these mobile casinos much more profitable for gamblers than the just-for-fun MiniTycoon: Casino.