Alrik Fassbauer and Sir Brennus spotted an article about the struggles of Tyranny to hit the sales target on PCGamesN:

Why didn't Tyranny sell? Paradox on Obsidian's RPG "everyone was hoping would do better"

Obsidian’s Tyranny is destined to be remembered as one of the boldest RPGs of the decade - not that anything so rote as destiny would figure into a world ruled over by an all-powerful but unseen genderless communist. It also felt uniquely timely, releasing as it did right on top of the election of a US president many believed had the potential to become a tyrant.

 

But even the combination of those factors couldn’t translate into mad sales. Speaking at Paradox Con in Stockholm this weekend, the company’s top figures voiced disappointment over what they know was a brave and brilliant follow-up to Pillars of Eternity.

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“Obsidian did a great job of capitalising on the timing of Kickstarter and the wave of nostalgia for these type of titles,” goes his hypothesis. “We've seen that most of the titles after Pillars of Eternity, if you look at Wasteland, Torment - they haven't been anywhere near that kind of success. So maybe it's that a lot of nostalgia fed into the initial bubble and that's why. These games have a market, but it's never gonna be that peak [again].”