Steam Early Access open-world Viking survival game Valheim is going strong. Really, really strong: 1 million copies sold in just 8 days after launch on February 2, doubling even more on February 15; as of February 25, Valheim has sold over 4 million copies, and the momentum doesn't look like it's stopping anytime soon.

Reaching 4 million players in less than a month is unheard of; as PC Gamer explains, previous viral hits like Playerunknown's Battlegrounds took months to achieve such sales. Even the once obscure indie title Minecraft, now a global phenomenon, has never achieved such an initial sales velocity.

So what is Valheim and why has it captured the hearts of so many? Here is the whole story.

Valheim is a survival game, which may seem familiar to anyone who has ever collected materials for crafting in a seemingly endless open world map. Yes, you will spend a lot of time sourcing parts, but it is not as rigid as in other titles, and recipes for new items appear as soon as you have the materials. Building is quick, easy, and satisfying, and even beginners can quickly build a good-looking fort.

The key here is simplicity. The ultimate goal is to defeat all of Odin's enemies, each of whom occupies a different section of the procedurally generated territory. Alone or with up to nine companions, the game follows a familiar pattern. Visit a new area, harvest resources, build new equipment suitable for the boss, defeat the boss, and then move on to the next target.

The key here is simplicity. The ultimate goal is to defeat all of Odin's enemies, each of whom occupies a different section of the procedurally generated area. Alone or with up to nine companions, the game follows a familiar pattern. Visit a new area, harvest resources, build new equipment suitable for the boss, defeat the boss, and then move on to the next target.

Combat can quickly become tedious routine work if not at the highest level, but fortunately developer Iron Gate has learned from the best, bringing an action-RPG feel to Valheim's combat. Attacks and combos vary by weapon type and weight, and you'll also master blocking, parry, and dodge-rolling to slice, dice, and slash your way through a variety of Norse mythological nasties.

If you want to play Valheim, you can get it for under $20 on Steam Early Access.

The five-person development team has certainly put in the work to keep up with player demand for more Viking content. Fortunately, Iron Gate has big plans, revealing its immediate Valheim roadmap in an interview with PC Gamer.

The first update is called "Hearth and Home," and as the name suggests, it's all about improving the home base with "more architecture and more things to do in and around the house," revealed Iron Gate co-founder Henrik Tornqvist.

Next up is an update to the intriguingly titled "Cult of the Wolf." This update "focuses on exploration and combat, and we hope there will be new fun and different encounters for players," Tornqvist says.

Those disappointed by the relatively empty waters will want to keep an eye out for the "Ships and Seas" update.

Closing out 2021 is "Mistlands," which will bring "new enemies, new items, new bosses, new resources, everything."

There are also many potential things the team would like to add, such as tar pits, phases of the moon, and a sandbox mode, which are very much in the stretch goal column for 2021 at the moment.

So no Xbox, Switch, PS5, or PS4 versions of Valheim. Not anytime soon, but in the long run it is possible. The game's FAQ states, "At the time of this writing, we have no plans to release the game on other platforms, but we do not rule out the possibility of a console version in the future."

The game already supports gamepad play, so that part is done, and the system requirements are relatively modest, so there's no reason why it couldn't be easily ported to the PS5, Xbox Series X or other consoles.

However, Iron Gate is a small team, and while the game is clearly making a lot of money now, it would certainly make sense to ensure that Valheim's popularity lasts for the next few months before hiring them for a console port.