Be wary when you chop down a tree in “Valheim.” Fans have learned this the hard way, running out of the way when chopping down a large tree only to have the trunk swing back — defying physics — and crush them.

If you’ve died this way, it’s not just the Norse gods who are laughing at your misfortune.

“We kind of hoped that the tree falling on your head thing would be a thing that many got to experience because it was kind of intended to work like that,” said Henrik Törnqvist, co-founder of Iron Gate Studios and designer on “Valheim.” “We find it pretty hilarious ourselves.”

“Valheim,” a Viking-themed survival game, has attracted frenzied attention from content creators and players with moments like these. The indie game, which was released as an early access title on February 2, commands a large audience on the PC games storefront Steam, at one time logging just under half a million concurrent players. Coming in just behind classic titles such as “PlayerUnknown’s Battlegrounds,” “Counter-Strike: Global Offensive” and “Dota 2,” “Valheim” is the most popular indie game on Steam, according to Steam Charts. Its publisher Coffee Stain estimates it has sold over five million copies, at $19.99 a copy.

“We’re still struggling to grasp exactly how big this can become,” said Sebastian Badylak, Coffee Stain Publishing’s executive producer.

The game is a potent combination of “Minecraft” and “Terraria”-like exploration and building features and combat that recalls the “Dark Souls” games. The player begins almost naked and in a field surrounded by rune stones. Collecting rocks and branches nets them resources to craft their first tools, which are useful for collecting food, crafting clothing and armor and eventually constructing a home. The world map is expansive, and as players venture further out, they face more challenging enemies across a varied landscape.

The attention the game has garnered in the past month has left the five-person team at Iron Gate Studio, based in Sweden, “quite overwhelmed,” said Törnqvist.

While supporting the game, “Valheim” developers have had to work some weekends and put in extra time. But the studio has a no crunch policy, referring to a practice in the games industry that involves working extensive overtime to make deadlines, according to Törnqvist.

Iron Gate is now hiring for another programmer, animator and a quality assurance manager to “handle the flood of incoming bugs,” Törnqvist said. But while Iron Gate is looking to expand, the developers have said they don’t see an acquisition in their future.

“The main drawback of working at the bigger AAA studio is that it’s very easy for individual employees to feel like just a cog in a bigger piece of machinery,” Törnqvist said. Having a small team means decisions get made quickly and fewer approvals are needed.

To keep fans entertained, “Valheim” developers are planning four major content updates this year, but “don’t have any dates yet for any of them,” said Törnqvist. One will focus on building, another will expand on exploration and combat, a third is focused on ships and finally, an update slated for later this year will aim to complete the Mistlands, an unfinished biome in the game.

“Valheim” may be in for some balancing, too. The bow and arrow weapon is “probably a bit overpowered right now,” Törnqvist said, adding, “it will probably get nerfed in a later patch.”

He said that after the studio has dealt with more serious bugs in the game, it will shift to adding more content — though to many, the bugs are a part of the game’s charm.

One particular bug that caught fan attention: Boats were mysteriously vanishing. One popular fan theory speculated that birds were landing on these boats and flying away with them, stealing them from players.

The developers aren’t so sure. “That would be great if that were the case,” Törnqvist said, chuckling. “But no, I simply think it’s the physics system. I think it has to do with the waves. In some certain situations, the boat doesn’t cooperate with the waves, and the physics gets all wonky and that’s why they fly away with incredible force.”

Ambitious fans have found ways to keep busy in the game. A Reddit user posted his replica of the Millennium Falcon in game, and another player recreated Sauron’s gloomy tower from the Lord of the Rings franchise.

“After playing the game for probably about a couple hundred hours, I just don’t understand how people can actually come up with these things, let alone execute on those ideas,” said Badylak, executive producer at Coffee Stain.

Some fans even started a player-versus-player tournament, toggling a feature that allows you to damage other players, and assembling teams to compete for three rounds.

“Valheim” is still mostly a player-versus-environment game and the player-versus-player mode is just for “bash[ing] your friends over the head,” but if it grows more popular, the developers will consider doing more with the mode, said Törnqvist.

The game has found popularity among players looking for experiences to share with friends. You can invite up to 10 players in a single game, and they can visit your structures and hunt bosses with you. You can also build portals and boats to explore the world further.

“We realize it’s important to keep players playing and giving them more to explore, more to build, more to do, basically,” said Törnqvist. “We’re working on adding more content as fast as possible. But that’s also the thing. No matter how much content you add in, you will always have people that are already done with it, basically on the same day. That’s something I’ve learned the hard way.”

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