Conquer Online is up there in popularity with Runescape. Best of all, it is free forever. The player base easily surpasses the million mark, and they have great PVP combat. There are four basic classes, the warrior, the trojan, the fire taoist, and the archer. Not many games like Runescape offer the qualities of Runescape, for free. The game can be run on almost any computer, however you do have to download a big client, which is not that big of a deal considering almost everybody uses broadband anyway. If you are looking for a great game like Runescape, I highly suggest getting signed up and checking it out for yourself.