Sandbox Mode is a mode in which no events will happen, and players are free to do as they wish. The Sandbox Panel is available in this mode, which allows players who were present at the start of the game to create items for themselves such as stacks of Metal and Glass, Gas Canisters, and other assorted goodies. It's an ideal mode to experiment around in if you're new to the game and want to figure out how to do things, or if there are few players around and you just want to fool about.