The original version of Assassin's Creed III is off of Steam and Uplay, at least for now. While the news is disappointing for fans, there's a silver lining; it means that the remastered version is coming to these platforms shortly, which is fantastic since the game is seven years old.
Uplay users reported not seeing the original version of the game on that platform and only the remastered version. On Steam, you can still see where the original version was stored, but the purchase button is gone and there is a short notice informing people that the game was yanked offline at the publisher's request.
Reports say that if you already own Assassin's Creed III on either platform, you can still download and play the game as usual (although your mileage may vary, as not everyone reported success). However, if you're looking to get the original and you haven't already shelled out, you're out of luck.
This shouldn't be too big of a shock for players, though. Other popular titles such as Sleeping Dogs and Deus Ex: Human Revolution also came offline when remastered versions were available. We can suppose that publishers don't want to confuse their audience by having multiple versions online, especially for those players who might be new to the franchise. However, this means that more experienced players lose the chance to compare the two through epic parallel playthroughs.
This means there might still be value in actually getting the hard copy of a game when you value it that much. We know that sounds like a shocking thing to say in this era of digital downloads and streaming, but think of platforms such as Netflix that pull movies and television shows when license agreements expire. If you really enjoy a game, there's no better way to guarantee your access to it than buying a physical copy and keeping it on the shelf.
While we lament the loss of the original version online, there definitely are benefits to playing the remastered version as long as your graphics can handle it. Its graphics are higher quality and there are also better options for gameplay, including more stealth opportunities, a better minimap, and more advanced assassinations. So, when it comes to battling those nasty Templars, you're going to have a lot more options ahead of you.