15.1 is an outdated version from Patreon. Once CK1 contained 4 Acts. Then Act 4 was reworked as Episode 1 in CK2 and removed from CK1. You can check out what the game used to look like, but playing an outdated version doesn't make much sense. It's better to start with the current version as you will most likely want to continue playing on your current save.What is the different between Act I - v1.2.6 and the Season 1 - v15.1 ?
Which one better for download?