https://bugs.freedesktop.org/show_bug.cgi?id=103850
--- Comment #6 from Michel Dänzer michel@daenzer.net --- The valgrind output for Quern shows writes to freed memory, because the game makes libX11 calls using a display handle that it had already closed. That's a bug in the game (or maybe in a library it links statically), which could explain the crash.
I don't see any obvious issue in the valgrind output for Unturned either though.