[@Shard] Well, Sandbox, in my experience, really doesn't require everyone to be active at all times, since it's more a case of the players try to tell their own stories within the world, whilst the GM sits there, throwing curve-balls at everyone.

"Say, that's a nice family you've been building development with, would be a shame if one of them was suddenly replaced with a Super Skrull that takes their place >:3"