Epic Games creative output has slowed down in recent months as it has put a lot of work into its Unreal game-creation engine, but the studio is ready to get back to its roots.

The developer revealed today it starts closed testing for Fortnite tomorrow. It’s a free-to-play base-building shooter where players work together to create a defensive structure during they day to fight off waves of enemies at night. This first playable session runs through Dec. 19, and Epic has started sending out invites to “select players.”

http://youtu.be/ncPK1r_igqk

Epic said it is picking players from its “Fortnite community,” but you can signup for a chance to get into the test later this week by heading to the official website. This also registers you for the opportunity to get into future Fortnite events.

“During this phase of the [alpha test], Epic is testing to verify at a larger scale that the basic systems in the game function properly, from sign-ups and patching, to gameplay,” reads an Epic press release. “Epic is devoted to taking its time and working with players to make Fortnite a great experience.”

Epic says it has a lot planned for Fortnite in 2015. For now, that likely means additional tests for more players. This week, as players start trying out the game for the first time, we’ll start getting an idea of how Fortnite works in action. We’ll also learn how its microtransactions work, since that is something of a mystery.

This is the first game from Epic Games Poland since 2013’s Gears of War: Judgment. The studio is probably best known for its creative shooter Bulletstorm, which had players blasting their way through different stages trying to score as many points as possible through the creative use of weapons and the environment.

With that pedigree, fans are curious to see how Epic Games Poland’s style translates into a free-to-play experience.