In 2012, Old Apparatus launched a bid for independence with their own Sullen Tone imprint to release their own projects and others. The first of these releases on the label were EPs that spanned the second half of the year, opening with the Derren EP before releasing a series of EPs from three separate members of the group. Compendium draws together the highlights of those EPs into a sequenced mix that draws the sheer drama out of the music, like contrasting scenes in a film, enabling the listener to pick out details in music and get lost in its generous sound world. It starts with "Zimmer's" rising strings and watery hiss, rolling seamlessly into the far away shoegaze of "Mernom" and then the warm, woodblock and acoustic guitar 2-step of "Derren." The mood switches up to the jungle atmosphere of "Dourado," with hypnotic drums and a feeling of panic, before the chopped and screwed march of "Lingle" drops the mood down with a club-footed hip-hop and ritualistic astral atmosphere before the album hones down into the bell-like melodies and sliding drums of "Boxcat." "Chicago" opens next with a bare piano and heartbeat thud, working out of the rainy atmospheres, while the shimmering drones of "Octofish" lead into the vast waves of "Realise," ending the album on a powerful note.