Thanks, Jens. That's some stuff to try...
I have been reading through the installer code. My frontend binaries are all 0 bytes, which is suspicious. Might try re-downloading the installer from Frictional, even though the installer is validating itself.
~/gam/tmp/bin/linux/x86/libc.so.6$ ls -lah
total 20K
drwxr-xr-x 2 user user 4.0K Sep 9 02:25 .
drwxr-xr-x 3 user user 4.0K Sep 4 18:27 ..
-rwxr-xr-x 1 user user 0 Sep 4 17:58 fltk
-rwxr-xr-x 1 user user 0 Sep 4 17:58 gtk
-rwxr-xr-x 1 user user 0 Sep 4 17:58 lock
-rwxr-xr-x 1 user user 8.9K Sep 4 18:27 lzma-decode
-rwxr-xr-x 1 user user 0 Sep 4 17:58 ncurs
-rwxr-xr-x 1 user user 0 Sep 4 17:58 surunner
~/gam/tmp/bin/linux/x86/libc.so.6$
Oh, jeez. Well, for me this error turned out to be caused by not-enough disk space.
Make sure you've got plenty of room for uncompressing those archives, folks!
Could the installer's error message be any less helpful?
Thanks for the help, Jens! You probably saved me a lot of time by linking those threads!