This is something so rudimentary that I'm a little embarrassed to ask, but I've also tried looking around online to no avail. One of the hard parts about being a Linux newbie is that the amount of support material out there seems to differ based on distro, DE, and also time, so posts from even a year or two ago can be outdated or inapplicable.
Here's my situation: I'm a newbie Linux user running Pop!_OS 19.10 with the GNOME desktop environment. Occasionally, games I'm playing will hard crash and lock up my system completely, leaving a still image of the game frozen on the screen indefinitely. The system stays there, completely unresponsive to seemingly any inputs. It doesn't happen often, but when it does it's almost always when I'm running a Windows game through Steam's Proton layer. I suspect it also might have something to do with graphics drivers, as I'll at times notice an uptick in frequency after certain updates, though that might just be me finding a suspicious pattern where none exists.
Anyway, what I don't know how to do is gracefully exit or recover from these crashes. No keyboard shortcut seems to work, and I end up having to hold the power button on my computer until it abruptly shuts off. This seems to be the "worse case scenario" for handling it, so if there is a better way I should go about this, I'd love to know about it.
EDIT: I really want to thank everyone for their help so far. My initial question has been answered, and for posterity's sake I'd like to post the solution here, to anyone who is searching around for this same issue and ends up in this thread:
CTRL+ALT+F3/F4/F5/F6keys to access a terminal, where you can try to kill any offending processes and reboot if needed.
- If that fails, use
With that out of the way, I've added more information about the crashes specifically to the thread, primarily here, and some people are helping me out with diagnosing the issue. This thread is now less about the proper way to deal with the crash than it is about trying to identify the cause of the crash and prevent it in the first place.