Albumen is a simple interface for viewing and playing songs (tracks) in your music library, organized into albums, podcasts, audiobooks, and playlists. Its chief virtues are: (1) song title and artist information is displayed in full, without truncation (unlike the Music app); (2) in addition to music, audiobooks and podcasts are displayed (unlike the Music app).
Tap a song (track) to start playing it. The iPhone's music player is used, so you can then quit Albumen and playback will continue, and you can use the iPhone's standard music interface to pause and resume play and so forth (including the Music app, the Control Center, and the lock screen). Albumen also includes a play/pause button and a track progress indicator. Albumen also tells you what track is currently playing: the album containing the currently playing track has a checkmark, and the currently playing track has a note mark.
Albumen ignores tracks without an album title, because album organization is its chief reason for being. Albumen ignores cloud-based tracks, because the system provides no coherent way of distinguishing their status.