Add custom spoilage categories

[AndreusAxolotl]

Usually spoiling in the Vanilla game only shows up with biological products, as expected, spoiling into spoilage or other products.

Modders though have used the spoiling feature to show other kinds of processes, from nuclear decay to rusting.

So my suggestion is the addition of spoilage categories.
These would function like burner types, while internally everything works under the same system, externally these would differentiate different "spoiling" processes.

The default category would, of course, remain "Spoiling", showing itself in game like it currently does.

06-29-2026, 23-12-54.png (9.62 KiB) Viewed 189 times

(Jelly as an example)

But if a custom category was declared it would be put in the ItemPrototype in a "spoil_category" field, spoil_category = "decaying" for example.
Spoiling categories would also be able to change the Icon that appears in the Factoriopedia tooltip, if possible code-wise, allowing for even clearer recognition by the player.

In the locale the modder would be able to specify the custom lines that replace the Vanilla spoiling text (spoil-time, spoil-result, percent-spoiled, spoilable, etc...) with fitting lines.

These are some mockups I made in Paint.

06-29-2026, 23-17-58.png (9.07 KiB) Viewed 189 times

(An Uranium isotope decaying into Uranium-238)

06-29-2026, 23-18-16.png (8.6 KiB) Viewed 189 times

(A hot version of a Tungsten Plate cooling down into the cold version)

This feature could also be used by the Vanilla game itself! Currently Biter and Pentapod eggs "spoil" into big biters or premature wrigglers, depending on the egg. With the addition of spoilage categories, this could be changed with them hatching!

06-29-2026, 23-19-54.png (8.43 KiB) Viewed 189 times

(Mockup of the hatchable spoilage category)

The addition of spoilage categories would also help modders make mods that interact with spoilable items.
These mods specifically interact with items that spoil organically.
https://mods.factorio.com/mod/spoilage-solution

These two also have a blakclist to filter out items that spoil, but are not organic.
https://mods.factorio.com/mod/planetaris-tellus
https://mods.factorio.com/mod/apia

The latter two mods can replace their blacklists with a type check to find organic items, and filter accordingly, ignoring interacting with custom inorganic spoiling, like the example "decaying" or "cooling".

Already existing mods like, for example, these two could also simply change the spoilage on their items to "cooling" and "rusting" respectively, making the new features they add feel more complete and make more sense.
https://mods.factorio.com/mod/hot-metals
https://mods.factorio.com/mod/Rocs-Rusting-Iron

[front]

I'm usually a strong critique of even my own ideas, so I rarely say this. This needs to be in the game.

This is not only added visual clarity (even for space age).
On the top of that it lets mods interact with each other in ways that currently can only be done either by custom apis (different one for each mod), a coordinated api (difficult to pull off), or by hard coding every modded item we know of.

I want this.

[FluidNatalie]

+1

Awesome feature idea

[Puke]

+1

[GN89]

+1

[Thremtopod]

+1