Screen space ambient occlusion was released on January 28th, 2011. The release of the shadows launched a graphics revolution on ROBLOX. They were released along with Updated Graphics. Ambient shadows are not yet supported on Mac, though Telamon (aka Shedletsky) states that a huge graphics overhaul that includes Mac support will be coming by summer 2013, but it never came. Ambient Shadows were replaced with dynamic lighting in 2013.