@PCGamer they take a look at Tibia. An MMO which has been going for 20 years and is still in active development.
More information."I'm happy and grateful that our student project has grown into such an MMO hit, supported by a very dedicated team and, most of all, by our wonderful players," says co-founder Stephan Vogler. "Even after 20 years we're not running out of ideas for Tibia-I'm sure the game will keep attracting players for years to come."