colinkeenan [1] filed a orphan request for monogame-git [2]:
This package has not been updated in 3 months and it cannot be compiled. The maintainer does not seem to respond to comments about it not being possible to compile it.
[1] https://aur.archlinux.org/account/colinkeenan/ [2] https://aur.archlinux.org/pkgbase/monogame-git/