From the blog "Sandbox Update Notes"
+ Added Settings UI
+ Added "Human" character type
+ Added "debug_char" character type
+ Added an additional easter egg world feature (currently not generated anywhere)
+ Added item: Torch
+ Added in-game chat (opened with T or /)
+ Added support for in-game commands, accessible from chat - type /help for a list of commands
+ Added commands: /help, /time, /update_lights, /version
+ Added tile-based lighting system
+ Added support for digging/breaking most tiles
+ Added font: