monster-masher is one of the last two packages in Debian unstable depending on esound. (And even if that were fixed, monster-masher depends on several other GNOME2 libraries that are being removed.)
monster-masher has been unmaintained usptream for 9 years. https://git.gnome.org/browse/monster-masher/log/ Maybe it's time for monster-masher to be removed from Debian? Thanks, Jeremy Bicha