Are there any changes to gameplay whatsoever? I'm mainly thinking about being able to choose a difficulty in single player but also things like not having Black Death have a chance to ruin your character(if your OCD, like me).

At least those two problems can be mitigated by save scuming and a bug if they weren't changed but it'd be nice if they were...

The bug, btw, is that you can set the difficulty of a single player game by starting a multiplayer game of the difficulty you want then exiting and starting a single player game. For that session, the difficulty of the single player game will be whatever you had the multiplayer game set at... That's one bug I hope they didn't fix, if they didn't add the ability to set difficulty directly.

Wow, I never knew about the Black Death thing.
I wonder how many hitpoints my old characters have lost over the time that I played it.

That rather sucks, to be honest. As if the shrines weren't bad enough already, but at least those can be ignored.

I was really hoping that they had added difficulty levels to the single player portion, but I kind of doubt it since they would have promoted that new feature on the main page.

TBH this GOG re-release is kind of meh, no true supersampling/downscaling for higher resolution monitors in 2019 is a big letdown, especially since a modder was able to do the same thing, for free I might add!

No changes have been made to the game code.