MarsSeed [1] filed a deletion request for opennx [2]: Abandoned since 2015; reported broken since 2017. Last release was in 2009.
Orphan dependency AUR/nx-common no longer has downloadable sources. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/opennx/
