Anomaly #0004 is a client made by an unknown bootlegging company back in 2008. It is currently unknown what country, when, how, and why the client was made. The only pieces of evidence is the screenshot displayed on this page, the website itself from early 2008, and the only known instance of a "RoBlocks Fun Client" within the archived website.

The screenshot depicted is a single frame of a lost video on xFire, where a player exploring a game within the Roblocks Client. It is unknown who the uploader of this video was, or how they got their hands on the game within the client, as the client that was archived does not have this place file within it.

We have determined that both the website snapshot and the download to the "Roblocks Fun Client" is deemed safe to explore. We still recommend that you enter with caution if you do decide that you want to explore "Roblocks.Fun".

Here is the link. Enter with caution.
RoblocksFun Snapshot

Update: Since the writing of this article, some new updates have come out about RoBlocks including a video of the client when it was up and the website. The video can be viewed here.