It takes light one year to travel 6 trillion miles. It takes Space Engineers one year to sell 1 million copies.

Today, developer Keen Software House, which produces the hard sci-fi astro-construction game, revealed that Space Engineers has surpassed 1 million copies sold since its release one year ago. The $20 game first debuted on the digital-distribution network Steam’s Early Access portal, which is for incomplete software that players can pay to start testing immediately. Since then, the sim has found a dedicated audience, largely through word of mouth.

Keen is just one of the most recent teams to prove that gamers are hungry for all kinds of experiences and that indie studios are often the best equipped to deliver on those consumer desires.

“We feel twice as happy with this achievement since it came on our first year anniversary since Space Engineers was launched to the public,” Keen chief executive officer Marek Rosa said. “This gives us double reasons to celebrate. We want to devote this accomplishment to our fans, whose encouragement and active participation made this possible. They have been beside us all along, giving inspiration for new ideas and supporting us with their valuable feedback. It is a great thing to have such an amazing community like ours.”

CGR Trailers - SPACE ENGINEERS Community Creations Video

While Early Access is an official channel on Steam, Minecraft developer Mojang popularized the concept for its phenomenally popular block-building game. It’s no surprise that Keen would want to emulate Minecraft’s release schedule since Space Engineers is a similar style of game. Both are first-person games where players must use resources to build structures. Both enable teams of players to work together to construct things in a multiplayer environment. And both have a survival mode that forces players to constantly deal with threats to their virtual lives.

By releasing on Early Access, Keen was able to slowly add these features over time. After selling 100,000 copies in its first three weeks, the company has used the money from its Early Access sales to build a fully functioning game that players can get on Steam right now.

In addition to the sales, Keen revealed that Space Engineers has 675,000 monthly active players, which is an impressive number for a hardcore indie game. While Space Engineers doesn’t rely on microtransactions and in-game purchases for its revenue, a large user base helps the studio make the game better. That’s a big benefit for a company that is continually trying to make its games better.

Space Engineers isn’t the first Early Access game to reach 1 million copies sold. Other hits include Kerbal Space Program, Day Z, and Rust.

Check out Keen’s full infographic for more details on the success of Space Engineers:

Space Engineers - 1 million Players!