An example would help.
Sorry it was not linked so I did not see it, yet:
Soundtrack book, why not. If it’s not enough explicit, we can always explain in release group annotation that it is a soundtrack album (although there is already the RG type that says that), and not an (image) album.
But here anyway, the soundtrack book release group (36 tracks) may not have been reused for the other two releases (apparently, extracts).
It seems they should not share the same release group.
I don’t remember if we include full length and extract of operas in same release groups, for instance.
But, well, if we choose to include full length and extracts in same RG, there is no real difficulty choosing the RG title, it’s the full length release title.
Most games don’t contain sound test menus nor audio CD tracks.
Games that contain Audio CD session (some Saturn and PSX games, for instance), I agree they can be considered releases.
Games that contain a SOUND TEST menu, well, erh, ach, it’s already a little bit far-fetched to consider them releases.
But the other games, really… I don’t think we can consider them as music releases, as you cannot buy it to play its music without playing the game throughout, each time you want to hear the final boss tune.
This is still not a release, it could be a recording series, or a bootleg release, if there is one