Roblox (partially found builds of online game; 2003-present)
An old logo from when Roblox wasn't public.
Status: Lost
Roblox is a massively multiplayer online game where users can create their own games for which other users can play. Before it was released to the public, it was known as Dynablocks.
Although the current version of the game is still up and playable, the clients from 2005 through 2007 have been lost. In July 2007, Roblox hosted a humorous video contest that many users entered, which is why we can find many videos from the lost 2007 clients. Only a handful of pictures and no videos from 2005 have been found so far, while the 2006 client has videos in the form of trailers and promotional videos since that was when the game was initially released to the public.
A patent released in 2005, which can be found here, shows some screenshots of the client and website from 2005.
In 2017, an installer for the 2007 client has been recovered, although it isn't possible to download the actual client as the original 2007 files have since been deleted from the Roblox servers. A download can be found here.
Gallery
Screenshot of the 2005 client
Early home page when the game was called Dynablocks
