Linkrealms is sandbox-like for the Ultima Online generation. I'm not a big fan, but I can see the appeal. I like lore driven worlds, where you feel like you're contributing to a battle during a great era. Sandbox MMO are difficult from design perspective, I never even saw a MUD/MARE back in the day that dynamically generated believable worlds. I saw a few that used keywords to populate areas when you reached the edge of a defined map (mostly BaronyMARE) -- but using the keywords, didn't create a believable world. The directional exits in the rooms were always random with no real fluency or meaning compared to a hand-spawned area. Standing in the middle of a desert, to walk northwest and find yourself in a lush forest, then north again to a frozen tundra was completely lame. Sandbox single player games are cake, sandbox building games are also easy enough (just a server hosted static generated world) ... but when it comes down to a large amount of players buying/downloading and installing a client and being dropped in the middle of things, you can't have much dynamic content. The best you can do is let the players make their own economy, and fight amongst themselves for regional dominance.