I just found a cool Dungeons and Dragons sandbox adventure on DriveThru RPG called "Gardens of Cavern Twelve". It's for D&D5e but, like all d20/D&D games, it can be adapted for pretty much any other D&D/d20 game, including old school roleplaying games. It seems to me that, although there is also an emphasis on character too, there is also a big emphasis on adventuring and some more old school thinking. The players play as escaped slaves who flee to a floating island and meet with all kinds of different encounters on the magical floating island. Very good sandbox adventure, full of different, very colorful personalities such as the half-orc Cavern Twelve and his gardens, which is where the adventure gets its name from, and a lot of history behind it.
Anyway, one of the best adventures I have ever seen, I hope people go and get it!
(Great art too!)
Link: www.drivethrurpg.com/product/280979/Gar ... ern-Twelve