I have to say this was the best update for me so far, amount of content was perfect for the development time. Update made me read every dialoge again and actually I care about the stuff happening once again.
This update was way better for me then that other game that had the halloween party.
Oh FFS Undergradsteve.. Im not even half way through the new update and i'm already getting pissed off at your continued lack of a Riley solo route.. ENOUGH!!
v15 is old "season 1", Act I is the rebuilt version of old season 1. So no, it's all separate. Unless you want to start from the very beginning, just play Act I first.
It's confusing but someone here explained it better.
Ren'py Tutorial on how to create PC/MacOS build.
To find my repacks use search function and just type MyRepack (much better search results than Compressed).