Here is the Headless Horseman's sales history in Roblox: October 31, 2013 - November 3, 2013; October 10, 2014 - October 30, 2014; October 1, 2015 - November 3, 2015 ...

The iconic "Roblox" "oof" sound has been removed by Roblox Corporation. This detail was announced by the game developer on July 26. Of course, many gamers were disappointed with the sudden change.