XCOM fans are going to have a busy day.

2K announced today that the free Long War 2 mod is available for its strategy game XCOM 2 on PC via the Steam Wokshop. It gives player a longer campaign than the original game (about 100 to 120 missions), smarter enemies, and new soldier classes. Although it’s a mod, 2K and XCOM developer Firaxis are promoting it directly and even partnered with Long War 2 developer Pavonis Interactive to help create it.

The first Long War was one of the most popular for XCOM: Enemy Unknown, adding new units, weapons, and campaign. Releasing a new one for XCOM 2 gives players free content to explore, keeping them interested (or bringing them back) long after the game’s release last February.

Although XCOM 2 is also out on PlayStation 4 and Xbox One, the console versions do not have mod support.

Gaming history is filled with other mod success stories. Both Counter-Strike and Team Fortress were once mods for the original Half-Life, with developer Valve hiring their teams to make new, official versions of their games. Valve also hired developers responsible for the Warcraft III mod Defense of the Ancients to create Dota 2, the second biggest multiplayer online battle arena in the world and one of the industry’s most lucrative games.

You can learn more about Long War 2 via a series of videos posted on Xcom’s official YouTube channel.