GLIBCXX_3.4.15 is an object in libstdc++.so.6.0.16.
( libstdc++.so.6.0.15 ? ).
'libstdc++.so.6.0.16' is part of gcc-4.6.x .
Not very smart to compile a game with the "compiler of tomorrow".
Slackware current has gcc-4.5.3 .
OS' with 4.6 : Fedora 15-16 , Debian Wheezy and Sid.
Solution : Compile gcc-4.6.2 with --prefix=/usr/local/gcc462/,
copy libstdc++.so.6.0.16 to /usr/lib64/,
and make a new symlink libstdc++.so.6 to libstdc++.so.6.0.16
Or grap libstdc++.so.6.0.16 from "libstdc++6_4.6.2-7_amd64.deb"
http://ftp.de.debian.org/debian/pool....2-7_amd64.deb
The package can be unpacked with 'ar -x <package> && tar xvf data.tar.gz'.
..