Allister BrimbleAllister Brimble is listed in the credits as one of the five loading music composers but although he did compose one tune for this game, it was not used.
Dimmu BorgirWhen Norwegian black metal band Dimmu Borgir released their 1996 album Stormblåst, one of the songs, Sorgens Kammer was a cover of Agony's title track. They never gave any credit to its creator though, and therefore the track was later replaced when the composer contacted the band.
IntroThe non-playable demo of the game contains following information: "After starting up with an over 50 takes long animated intro sequence Agony will lead you through 6 worlds." The problem is that there is no intro sequence in the final release of the game. Franck Sauer (from the development team) was kind enough and provided precise information about the missing intro for Agony:
There was an animated intro sequence that was supposed to be included into the game and explained its backstory in more detail. That sequence had been animated by fellow artist Marc Albinet but didn't make it into the game mainly because it would have required one or two more disks and given the quality wasn't really on par with the in-game art, Psygnosis and Yves Grolet (lead programmer) decided it was not worth it."
MusicTim Wright composed two tunes for this game but "title" tune was not used in its original version and "high score" tune was not used at all.
When he sent the tune off for inclusion in the game, Franck Sauer (from the development team) changed the piano samples in it for better ones. However, one of them was at the wrong octave. Wright did not find out about these changes until the game hit the shelves and as he states: "Maybe people like it but it always sounded wrong to me". He eventually released both unused "high score" tune and the original version of "title" tune on December 10, 2001. They can be downloaded from his personal website (in one 7 MB big archive with all other tunes he created on Amiga) or from Exotica.
OwlThe owl controlled by the player, is actually the one from Psygnosis' logo.
Information also provided by B.L. Stryker and M4R14N0