I upgraded to OS X El Capitan recently, and now when I try to open Avernum 1 I get this message:

The application X11 could not be opened.

An error occurred while starting the X11 server: "Failed to activate core devices."

Does anyone know how to get around this issue?

Thanks!

Are we talking Avernum 1 or Avernum: Escape from the Pit?

Avernum 1. Coincidentally (or maybe not so coincidentally), I get the same message when I try to open Alpha Centauri: Alien Crossfire.

Sounds like the wrappers are pointing to out of date window system. Unless it's a native app but that doesn't change much then. Did OS X change the windowing system with El Capitan, or is it still Quartz?

Thanks Darvond, but I'm afraid I don't really know much about computers - I have no clue what wrappers and windowing systems are.

I did look up XQuartz though and installed it. After some fooling around in Wineskin, I figured out that if I force it to use XQuartz instead of X11 and then do a test run, I can get Avernum to play in a small window. Now I'm trying to figure out how to get it to play full screen.

I tried the same approach with Alpha Centauri, but the results aren't so good - the game opens in a black window. I can hear the game playing, but can't see anything!

Try re-downloading and re-installing the game. There have been a lot of reports of problems with Avernum games on El Capitan recently, but some users report that updated installers from GOG have fixed the issue. I've also heard that launching through GOG Galaxy instead of directly launching the game might help.

Make sure you back up your save files first.

Thanks Waltorious.

I downloaded the current version of Avernum and it now opens and plays just fine, but whenever I try to load a save file it crashes! Ugh...

Are these saves from before you reinstalled the game? Maybe the saves are not compatible with the updated version. Which would be really annoying.

If not, I'm not sure what else to try. You can contact GOG support through the "support" tab at the top of the website and see if they can help.