You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in ogamesim 's PO files:

gettext: www/template/lang/cn.po: cn not a language code
gettext: www/template/lang/cz.po:77: keyword "Vlo" unknown
www/template/lang/cz.po:77:13: syntax error
www/template/lang/cz.po:78: end-of-line within string
msgfmt: found 3 fatal errors
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.