Sandbox, or s&box, is the heir apparent to Facepunch Studios' Garry's Mod. We first started hearing about it again last year, thanks to a meme-y tweet from Garry Newman, but since then its gotten a proper website with real development updates. The latest development update goes quite in-depth, explaining progress on Ragdolls, various sandbox tools like wheels and thrusters, chatboxes, pretty water, breakables, and perhaps most impressively: The sun.
"This month I've started working on an extense time of day system," Newman says in the update. He goes on to detail the graphical changes that the light system allows, like matching shadows on both the player model and what's in the player's hand. There are a lot of great little videos in there, from how ragdolls work to how things are affected by physics and break. And emojis in chat. That's nice too.
We first heard about Sandbox nearly three years ago, when Newman wasn't quite sure that this code would become Garry's Mod 2. And it's possible that it didn't, since the game has switched engines and seen development start and stop several times since then. Garry's Mod is the most popular physics and nonsense sandbox for the original Source engine, and the tale of the total accident that lead to its creation is a fascinating read.