Metal Gear Solid V: Ground Zeroes and The Phantom Pain have seemingly never been cheaper as one can subscribe to Humble Monthly and get both games for 12$, along with Cities Skylines and a group of other, for the moment unannounced games.
Many fans were outraged back in 2014 when Hideo Kojima & co. pulled a sneaky on them with Metal Gear V: Ground Zeroes. No one was mad at the game per se, since pretty much everyone enjoyed it, but everyone hated how short it was. Basically it was a glorified demo for Metal Gear V: The Phantom Pain but the tensions eventually died down.
Together they make a pretty nice AAA purchase and are the last Metal Gear Solid entry that was made by Kojima and his team. Considering that they are only $12 on Humble Monthly at the moment, it is a pretty good purchase, especially if you haven't played any of those two games before.
Naturally, these two games do not make up the $100 value that Humble promises for their bundles, so they are just two games on December's roster. Currently, there is only one more revealed game which is Cities Skylines, with more to be revealed on 07 December 2018.
In case you are not familiar, Humble Monthly subscription grants access to the Humble Trove that contains DRM free and you can play them as long as the subscription lasts. You can cancel the subscription at any time, but access to the trove remains until the current subscription runs out.
It features several gems, such as Limbo, Trine and Torchlight II, so if you subscribe in order to get the Metal Gear Solid V duo, make sure you try some of the free games too.