Here's a suggestion for anyone with a crash issue.

I was experiencing a repeatable crash in X3 Reunion during the first mission on Linux (mostly up-to-date Arch). On a whim I decided to try replacing the bundled libraries in the lib/ and game/lib/ directories with packed ones and 2 I had to build my self. Surprisingly that fixed the crash and I was able to finish that and eventually dock at a station so I could save after the mission.

I had to build ffmpeg 0.9.4 and GLEW 1.9.0. Fortunately I know ffmpeg and think it is easy and GLEW just needed a minor change to the lib32-glew PKGBUILD. I renamed the two directories to lib.old and copied my newly built libavcodec.so.53 libavformat.so.53 libavutil.so.51 libGLEW.so.1.9 libswscale.so.2 into a new game/lib directory.

Now I can fly in space.

Same as with the other old X games on GOG for Linux.

I spoke too soon. I now get a crash when loading that game. Maybe I'll stumble across the solution for that one day.

What's the error output of the crash? You've probably thought of it already, but if you run the program from a shell it should be able to show you error output, rather than starting it from a shortcut or app launcher depending on your environment. Maybe it has a log file too: I'm not familiar with the game, just browsing the forum. You could also try the "objdump" or "ldd" tools to see how the program binaries are linked to libraries. Other tools can do that too, but "ldd" has many less flags than "objdump" for example.

edit: and maybe it's overkill, but if there isn't a good log or error message, you could try to start the game from inside of "gdb" or a different debugger. There are some GUI frontends to gdb, such as "ddd" (not to be confused with "dd", heh) There's also "strace" and other tracers, which could give you an idea of where the crash occurs. If the game is running within gdb, when the crash happens GDB should let you investigate the function call stack (backtrace) and things like that from an interactive prompt: how it got to where it failed, as well as the status of the machine registers and memory.