MUDs / MMORPGs, based on the Diku Mud software. They aren't hugely popular, but there is a very loyal playerbase. One of our games averages 200 players online at all times and we have 400 people registered for the new one thats opening next week. Its definitely a "niche market".

The ones that I've worked on are all free online multiplayer platforms, a genre unto itself, lol. They are all loosely based on a system of character development like Dungeons and Dragons.

Rhos