What we include
There isn't one feature that automatically makes a game a sandbox. We're looking for persistent MMOs built around player freedom: things like open-ended progression, player economies, crafting, housing and construction, territory control, politics, sieges, terraforming, or open-world PvP.
A game doesn't need every one of those features to be here. Something like Puzzle Pirates looks very different from Mortal Online 2, but both give players systems they can use to create their own goals instead of simply following a set path from quest to quest.
We don't include every survival game with crafting and base building. The MMO part matters too. In general, the game needs to have a persistent shared world built for a large community of players rather than a collection of small private servers.
What about dead games?
They're here too. Games such as the original Darkfall are an important part of the genre's history, so we keep them in the database even after their official servers close. They just don't appear in the default active-games list.
Private servers and emulators
For now, the main database sticks to official releases and commercial revivals. Private servers and emulator projects can still be mentioned on a game's page when they're relevant, but we don't list each one as a separate MMORPG.