Fantasy lives are certainly nothing new. Elaborate imaginary worlds, conjured up in stories and songs, are probably as old as humanity. Even participatory fantasy worlds are hardly new; ordinary board games (like chess) create a virtual reality in which the players assume virtual identities (like king, bishop and pawn), and in which they stalk each other according to well-defined conventions. A generation ago the scope of these fantasy worlds was greatly increased. The game Dungeons and Dragons enabled more players and less convention, leading to what was possibly the first viable large-scale social fantasy world. But the Internet has taken fantasy worlds to a whole new level. The most popular open-ended fantasy world, Second Life, enables tens of thousands of users to manipulate human-like figures called "avatars" through a virtual reality the creators try to make as similar as possible to real life. SL avatars meet, interact, work, buy, sell and even get married and, alas, divorced. It also enables them to create street gangs, engage in fraud, and simulate similar behaviors we experience in Real Life (or RL, as it is known in virtual reality circles). These virtual worlds stimulate a number of fascinating ethical questions. The first being, is it ethical at all to escape from real life into an extended fantasy existence? I dealt with this question in one of my first ethics columns and in my book. The answer, in my view, is that it depends whether it interferes with the participant's ability to maintain stable RL relationships and a stable RL identity. I suggested that adolescents, who are still forming their identities, need to pay particular attention to avoid developing a fantasy identity at the expense of a RL one. But the problem does not stop with youngsters. For years, news media have been reporting about the worrisome phenomenon of "virtual affairs" - people who have prolonged intimacy over the Internet. Sometimes the other side is a kind of "pen pal" whose true identity is known. With increasing frequency, it is a fantasy character who achieves intimacy with another fantasy character. The participants generally view these parallel relationships as harmless, but real-life spouses (male and female) do not always agree and these affairs have been implicated in a large number of divorces. In this column I want to focus on one specific aspect of virtual ethics: virtual behaviors that are permitted by the rules (and physics) of the game space, but which simulate activities that are forbidden in RL - for example, the street gangs that reportedly are terrorizing some locations in Second Life. Is it ethical to mug someone in a virtual world? In my opinion, the answer is yes. The whole idea of these parallel universes is to enable people to do all kinds of things they fantasize about but don't care or dare to do in RL - mostly things I cannot mention in a family newspaper. Evidently, for many people, this includes joining a street gang or engaging in other kinds of aggressive behavior. Of course there are virtual reality games that are explicitly designed to simulate these behaviors, such as the video game Grand Theft Auto in which the player can take on the role of a criminal, or World of Warcraft, which enables the participant to play a warrior. But that doesn't mean they have no place in a general-purpose virtual world. If these games want to prevent such activities then they can make refraining a condition of participation. In response to these behaviors, denizens of these worlds are considering various virtual solutions, including vigilante justice and ultimately proposals for having a virtual police force and court system. Even if these are created, I don't see how it would make virtual crime unethical. Having virtual cops hunt down virtual crooks merely makes the fantasy world more realistic. Again, if users decide that this is one aspect of life they would rather leave to RL, this can be made a condition of participation. Of course there are some reservations. For example, it seems like some kinds of "virtual crime" in these worlds is driven by RL crime. Since there is real money to be made in some of these games (especially Second Life), RL gangs may engage in aggressive behavior to make money. I am certainly not condoning this. But if a genuine fantasy gamer decides that he wants to play thug instead of some other imaginary role, that seems to me to be a realization and not a frustration of what these virtual environments are all about. In fact, I think that the realization that behind the terrifying attacker on your screen there may be a harmless 90-year-old RL grandma will help gamers to keep perspective, remember that it's just a game and maybe even "get a (real) life." firstname.lastname@example.org The author is research director at the Business Ethics Center of Jerusalem. (www.besr.org), an independent institute in the Jerusalem College of Technology.