Civilization 6, the most recent entry in the turn-based strategy series, was released on iPhone this year after a full port to iPad in 2017. Today, publisher Aspyr announced that all expansion packs for the iOS version of the game will be available for free through the rest of December.

Rather than releasing them all at once, a new expansion will be free for iOS users every 48 hours. Starting today, Dec. 20, the Poland Civilization and Scenario Pack is listed as $0 in the in-app purchases tab. On Dec. 22 it will go back to full price and the Vikings Scenario Pack will be free until Dec. 24 and the next game will be free and so on until Jan. 1. Once downloaded, the expansion is yours to keep forever.

The schedule for the free expansion packs is listed below. The base game is required in order to download each expansion. Civilization 6 is free for the first 60 turns, then costs $14.99 to unlock the full the game.