This is a topic on one of the better sandbox games: Garry's Mod.
For anyone who hasn't played Garry's Mod(Gmod for short) its basically a open source game where you're given every prop from every valve game(Half-Life,TeamFortress2).The objective is to do whatever you want. However, there are some servers that have custom games modes(ex: prop-hunt,flood,Trouble in Terrorist town).
So go ahead and discuss Gmod stuff like:
-Favorite thing to do in single player.
-Good workshop addons.
-Cool custom game modes.
-What's the secret word(achievement)?
and anything else about Gmod.