Factorio Forums

https://www.factorio.com/blog/post/fff-407 talked about "variable music tracks". There have also been several mentions of this in subsequent patch notes.

My understanding after reading that FFF was that all the music for the new planets would be procedural, but after hundreds of hours playing Space Age I'm not sure.

Can anyone shed any more light on what the deal is with variable music? What actually is it, when does it happen and how can you tell?

Also, how does this relate to the purchasable Factorio soundtrack which obviously can't be procedural?

Variable Sound and the planet property was added in version 2.0.7.

Ambient sound definitions can be found in space-age/prototypes/ambient-sounds.lua. Variable tracks eg, data/space-age/sound/ambient/aquilo/aquilo-1/aquilo-1.lua make use of multiple layers and variants. Some tracks are static, eg aquilo-2 is a single .ogg file.

According to FFF-435:

The selected tracks have been remixed to enhance and intensify its dynamics to give them a proper album format experience. All the recording sessions with the musicians and the electronic compositions are paying off here. Many sections of tracks that were originally composed but cut from the final game tracks have been released in this album.

Good Luck!

SystemParadox wrote: Wed Jan 14, 2026 4:36 pm My understanding after reading that FFF was that all the music for the new planets would be procedural, but after hundreds of hours playing Space Age I'm not sure.

The procedural music is only a small part of the whole soundtrack. Most of the music are regular tracks. There are 10 procedural music tracks out of the total of 50 tracks. I could have done a better job in communicating that in that blog post, even though at the time of writing the blog the number of tracks wasn't yet decided.

SystemParadox wrote: Wed Jan 14, 2026 4:36 pm What actually is it

It's what it said in the blog post. They are tracks that will play out a little bit differently each time they play, using multiple layers and randomization of audio samples, following a set of rules.

SystemParadox wrote: Wed Jan 14, 2026 4:36 pm when does it happen

It's a random selection with a little bit of weighting.
And procedural music is only in Space Age. There are no procedural tracks playing on Nauvis.

SystemParadox wrote: Wed Jan 14, 2026 4:36 pm how can you tell?

If you enable the "show-detailed-info" debug option, it will say whether the currently playing music track is procedural (variable) or regular (static). It also shows the name of the track.

SystemParadox wrote: Wed Jan 14, 2026 4:36 pm Also, how does this relate to the purchasable Factorio soundtrack which obviously can't be procedural?

The procedural tracks included in the standalone OST are one possible version of each track.

eugenekay wrote: Wed Jan 14, 2026 5:26 pm According to FFF-435:

The selected tracks have been remixed to enhance and intensify its dynamics to give them a proper album format experience. All the recording sessions with the musicians and the electronic compositions are paying off here. Many sections of tracks that were originally composed but cut from the final game tracks have been released in this album.

Note that this refers specifically to Disc 1 of the standalone OST. These are tracks specially selected and remixed for a standalone album and are not present in-game. Disc 2 contains all tracks that are in-game.