Multiplayer survival games are still a huge category on Steam and PC, and the latest darling of this genre has reached a new milestone.

Ark: Survival Evolved has reached 2 million copies sold, according to Studio Wildcard. This open-world online multiplayer game has players trying to scrape together enough resources to survive in a world filled with dangerous enemies and dinosaurs. Wildcard is using its success to continue building out the features in Ark. Every week, the studio adds more content, such as new dinosaurs.

Wildcard is the most recent developer to benefit from the huge thirst for this kind of game on PC. Previously, games like DayZ and Rust have sold millions of copies by providing similar experiences on Steam. And like those games, Ark is still in Early Access on Valve’s digital-download platform. This means that Wildcard hasn’t finished its survival simulator, and it is still actively developing it.

In a question-and-answer session on the community forum Reddit today, Studio Wildcard co-creative director Jesse Rapczak explained some of his philosophy for approaching early access.

“Early Access is a privilege, not an excuse,” he wrote. “[Developers should] have a plan to finish the game and communicate it clearly.”

Rapczak has also seen the importance of daily and weekly updates to prove to the community that their support (and money) is going to features they care about.

“Respect peoples’ time, and treat the game like a launched product,” wrote Rapczak.

By that, the developer means that if people are paying for a game, they’re going to have certain expectations. Chief among those expectations is that things people do and achieve in a game will last.

“As much as possible, don’t wipe progress or take back from the community,” he said.

With those principles, Ark has spent months at or near the top of the Steam sales charts. And it could even sell a hell of a lot more when Wildcard makes the move to release the game in Early Access on Xbox One “this winter,” according to the studio.