Steam ships with it's own gcc libraries, which are outdated and do not work on distributions with newer libraries. For further information, check out:
https://wiki.archlinux.org/index.php/steam#Steam_runtime_issuesTo solve your problem on Ubuntu 14.04, close Steam and run:
rm ~/.local/share/Steam/ubuntu12_32/steam-runtime/i386/usr/lib/i386-linux-gnu/libstdc++.so.6
rm ~/.local/share/Steam/ubuntu12_32/steam-runtime/i386/lib/i386-linux-gnu/libgcc_s.so.1
rm ~/.local/share/Steam/ubuntu12_32/steam-runtime/amd64/lib/x86_64-linux-gnu/libgcc_s.so.1
rm ~/.local/share/Steam/ubuntu12_32/steam-runtime/amd64/usr/lib/x86_64-linux-gnu/libstdc++.so.6
rm ~/.local/share/Steam/ubuntu12_32/steam-runtime/i386/usr/lib/i386-linux-gnu/libxcb.so.1
On 14.10, the path changed, commands are similar:
rm ~/.steam/ubuntu12_32/steam-runtime/i386/usr/lib/i386-linux-gnu/libstdc++.so.6
rm ~/.steam/ubuntu12_32/steam-runtime/i386/lib/i386-linux-gnu/libgcc_s.so.1
rm ~/.steam/ubuntu12_32/steam-runtime/amd64/lib/x86_64-linux-gnu/libgcc_s.so.1
rm ~/.steam/ubuntu12_32/steam-runtime/amd64/usr/lib/x86_64-linux-gnu/libstdc++.so.6
rm ~/.steam/ubuntu12_32/steam-runtime/i386/usr/lib/i386-linux-gnu/libxcb.so.1
or
rm ~/.steam/bin32/steam-runtime/i386/usr/lib/i386-linux-gnu/libstdc++.so.6
rm ~/.steam/bin32/steam-runtime/i386/lib/i386-linux-gnu/libgcc_s.so.1
rm ~/.steam/bin32/steam-runtime/amd64/lib/x86_64-linux-gnu/libgcc_s.so.1
rm ~/.steam/bin32/steam-runtime/amd64/usr/lib/x86_64-linux-gnu/libstdc++.so.6
rm ~/.steam/bin32/steam-runtime/i386/usr/lib/i386-linux-gnu/libxcb.so.1