Public Service Announcement: Debian helpfully defines
datadir to be
/usr/share/games for some packages, which means that the AppData and MetaInfo files get installed into
/usr/share/games/appdata which isn’t picked up by the metadata parsers.
It’s probably safer to install the AppData files into
$datarootdir/appdata as this will work even if a distro has redefined
datadir to be something slightly odd. I’ve changed the examples on the AppData page, but if you maintain a game on Debian with AppData then this might affect you when Debian starts extracting AppSpream metadata in the next few weeks. Anyone affected will be getting email in the next few days, although it only looks to affect very few people.