I am super sad for not being able to play Frostfeast anymore with a20 release - I have so much I still want to do in my game. Is there a way I can keep playing it? I see there’s an a19 vista version build on steam - but is that only for Windows Vista? I have Windows 7.
No, that A19 version is the same as the previous A19, you can play it.
That branch is called Vista because it was made so that Vista users can still play that version, since we don’t support Windows Vista any more starting from A20, and they might still want to play the game before getting new systems or upgrading their OS. But anyone who wishes to play A19 is free to use that version
Be careful when switching, A20 saves won’t work on A19.