Turns out, pinning down the number of people who have bought Amnesia: The Dark Descent is difficult, according to the developers. Why? The Humble Indie Bundle included the game, and that sold like hotcakes. Okay, that doesn't sound like it would make things more complicated, but it does! Here is how:
Without counting the units bought there our total lands at 710 000 units. Adding all HIB and Potato Sack sales gets us to 1 360 00 units in total, which can be called the optimistic figure. This means that, optimistically speaking, Amnesia has sold almost 1.4 million units! This reasoning is not strictly speaking invalid, but I think that one should not really count anyone that bought the bundle and already owned Amnesia as a proper unit. A slightly pessimistic guess (not far from reality I think) is that 2/3 of every bundle and pack buyer already owned Amnesia. This gives us about 920 000 units in total, pessimistically speaking.
It's an educated guess, to assume x number of people already owned Amnesia before buying the bundle–so we can't be certain how many people actually bought the game. Just how many copies of the game has sold. It's semantics, but still, makes you think, especially in regards to bundles and games that make regular appearances in them. How many people actually own the game and how many are buying the game a handful of times?
But more interestingly, the devs state that every 5 minutes, someone buys Amnesia. Every five minutes! It's higher right now than it was around launch–also insane.
The devs also talk a little bit about what's in store for Amnesia's future, which you can read here. Don't bother going there if you want to read up on piracy and Amnesia, though. They don't say anything about that.
