"All sentient beings will kneel before me!"
Little is known about PROJECT: NEMESIS PRIME. Recently certain intercepted Decepticon cominiques [sic] lead Autobot High Council 
to believe that this is yet another attempt to generate an Optimus Prime clone. But according to the seized transmitions [sic], upon completion, Nemesis Prime was commandeered by the despotic Decepticon petty tyrant, Straxus. After this incident, there has been no further mention of Project: Nemesis Prime.
At BotCon 2011, there was a set of posters, "The 'Bots and The 'Cons," featuring retro-style tech specs for a bunch of TF Animated characters who may not have appeared on the show, but had still been designed by Derrick J. Wyatt; that's where the above text comes from, making it as official as possible without being official. The combo of "built as a secret project, then disappearing" and "Straxus is doin' stuff" seems like a combo of the Alternators and Classics bios.
This is the Legacy United "Animated Universe" Optimus Prime mold, because what else would it be? There was an official "Optimus Prime Black Ver." released in 2010, but it was only available during an in-store promotional event at a single location for six days in August, and was limited to 300 pieces. 
So even as part of an exclusive four-pack, this one is at least... (approximately 2,000 Target stores in the US, every store got six sets, round up to put a few on Hasbro Pulse...) 50 times more plentiful.
The colors on this version are similar to the Japanese exclusive, but not identical: like, it's black and silver, with red windows, but the blue stripes go the entire way along the side instead of turning silver halfway in. Plus, instead of being solid black, his hands have blue fingers and red panels on the back. He's carrying the same extendable axe as the Legacy figure, with a translucent red blade, and in order to set him apart from Optimus, he gets a head with the mouthplate up.
Because all the plastic is so dark, it can be hard to tell when you've got tabs properly lined up with slots to lock his parts into place. And one of the front bumper sections keeps wanting to fall out of his ribs when he's in robot mode. But I love Animated and I love Nemesis Primes, so you know I absolutely love that there are now more than 300 of the toy in existence.
