Subnautica: Below Zero hits number one on the Steam game charts just after hitting early access.

If you haven’t played Subnautica, stop reading and go play it. It’s anywhere from 50 to 100 hours, depending how much exploring you do, so we’ll be patient while we wait for you to return.

Done that? Okay, good. Now the stand-alone expansion, Subnautica: Below Zero, is out in early access. You should go play that one too.

It’s only about 2-4 hours of gameplay, however, so we won’t have to wait nearly as long for you to get back to reading this highly informative article.

Done? Great. Now for some even better news: that 2-4 hours of early access gameplay is the number one selling game on the Steam Charts last weekend. And it only went into Early Access on January 30th.

Is that great news for the developer? Absolutely. Imagine outselling a blockbuster like Resident Evil 2, a game that costs three times as much, in the first week of sales. And just note that out-grossing Resident Evil 2 means that over three times as many games were purchased on Steam than the Capcom reboot.

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And also keep in mind this is a still a very early build of the game--some would even call it an early alpha. The core gameplay is present, and there’s a lot of polish on the environment as you’d expect from the same people who made the original Subnautica, but the game is still very, very rough. There are bugs, poor framerate, and “frequent but often not game-breaking” issues that can come up, requiring every player to save as often as possible.

We don’t know much about Subnautica: Below Zero because the game still isn’t built yet. We know it takes place in a polar region of the same planet (4546B, for the Subnautica faithful) and we know there are a lot of new mysteries to discover based on the planet’s alien inhabitants. We’ll find out more as the game is developed.

How long will that take? Who can say? Subnautica was in Steam Early Access for just over three years, so expect this one to take maybe a few months less given they’ve got a head start this time.

NEXT: JUST WHEN YOU THOUGHT IT WAS SAFE: SUBNAUTICA: BELOW ZERO EARLY ACCESS STARTS JANUARY 30