problem lies in symlink /usr/games/openttd -> ../share/games/openttd/openttd
to correct this:
rm /usr/games/openttd
ln /usr/share/games/openttd/openttd /usr/games/openttd -s

or alternatively you can edit /usr/share/applications/hildon/openttd.desktop and correct Exec= line.

i also needed to unpack sample.cat from original ttd to /opt/openttd/data