Shortly after Project Metaverse came to its fruition, Earth's government gave an order that has puzzled humans, sprites, and Anthros alike for decades afterwards. Three of the colony worlds, designated "Omega class," were ordered to be completely shut down. No satisfactory reason for this order has ever been given. All kinds of theories have been put forth, but the generally accepted idea is that these worlds were, for one reason or another, unfit for human habitation, and the government had them shut down for the public's safety (and also to cover the butts of the scientists who programmed them).
Rumors abound about the three Omega class worlds. Some say that they were populated by horrible monsters; others say that they contained strange microbes that gave the initial scouting parties a mysterious and incurable disease. Still others say that the Omega class worlds weren't really shut down at all--that they were merely cut off from contact with Earth or cyberspace, and that the government is keeping them on-line for some unknown purpose. However, no solid facts are known about the Omega class worlds, and the true reason for their deactivation remains a mystery to this day.