It is as current (if not newer) as the main project so I would say stale rather than abandoned, unless they migrated elsewhere or XMP is dead.
http://xmp.sourceforge.net
The current stable version is 4.4.1 (released Oct 12 2016).
The Windows version of XMPlay had 1 update last December since an update in 2018, so don’t expect much activity if it isn’t relevant to the android version.
However that aside, can we please have the newest version in F-Droid ?