L5R RPG Sandbox
I feel like it could run very well as a sandbox but you’d have to change the theme somewhat. If the players were a band of ronin(probably not built as such, but thematically) or the party was evil then sure. Or if it was during one of the clan wars and all the players were from the same clan or allied clans. I just don’t see the group of mates from different clans that the standard campaign portrays as a good setting for sandbox but I could be wrong. That being said I would love to try even if it was the standard pal adventures, with a preference for 4e.