Magic: The Gathering Online

Magic: The Gathering Online (MTGO) or Magic Online is a direct video game adaptation of Magic: The Gathering, utilizing the concept of a virtual economy in order to preserve the collectible aspect of the card game. It is played through an Internet service operated by Wizards of the Coast, which went "live" in June 2002. Users can play the game or trade cards with other users. It is only officially available for the Microsoft Windows operating system.
As of February 2007, Magic Online has over 300,000 registered accounts; however this does not represent the true number of players, since people are allowed to register multiple accounts. At different times during the day and night, Magic Online hosts on average 2,000-4,000 simultaneously logged in accounts; according to the developers, there is a hard limit of 4,400 players in version 2.5.
According to Wizards of the Coast, Magic Online is "somewhere between 30% to 50% of the total Magic business."
Magic Online is played as an electronic analogue to the physical card game. Digitized artwork reproduces the look of a card game, while users click on cards to play them on a virtual tabletop. Each game is hosted by the server, which applies a rules engine to enforce proper play. The logic for handling card interactions is provided by Perl scripts. Though the rules set as a whole is largely accurate and works well enough for production, it occasionally suffers from bugs. Similarly, built-in engine limitations frequently impose clumsy user interface characteristics such as having to click away a large number of pop-up windows that can be generated by certain cards. This is one of the issues being addressed by the revamped version 3 software.
Players are free to setup or join games of their choice. In addition, official events such as leagues, drafts and tournaments take place according to a regular schedule. Entering events requires an investment of sealed packs and/or event tickets, but winners are also rewarded with additional product. Some players equate this to gambling.