Food spoilage

Stored Food does not vanish - it ages. Every night a share of your stored Food turns to Old Food, and a share of the Old Food you hold rots away to nothing. Old Food still feeds colonists, but it goes on rotting and dwindles the longer it sits.

The two nightly steps

Where it happens

Food ages in every store that holds it: a Universal Storage Depot, a Food Depot, a Diner or Grocer (each keeps its own Old Food store and serves it first), an RC Transport or RC Constructor carrying Food, and loose Food piles lying on the ground.

What the new Old Food does depends on the store:

• A store that holds Old Food beside the Food (Universal Storage Depot, Diner, Grocer, rover) turns the aged Food into Old Food in place, up to the free Old Food space. If more Food rots than there is space for, the extra Food is simply removed - nothing piles up outside.
• A Food-only Food Depot, or a loose Food pile on the ground, has nowhere to keep Old Food beside the Food, so the Old Food drops as a pile on the ground beside it, rounded down to whole units. A night's rot of less than one whole unit leaves no pile, but the Food is still removed.

Eating Old Food

Colonists eat the older stock first. At a Diner or Grocer the Old Food is served before any fresh Food. A starving colonist with no Diner or Grocer in reach eats from the nearest depot or ground pile instead, Old Food or fresh alike, whichever is closest (out here there is no preference between the two). Eating raw this way costs -3 Comfort, the same as grabbing fresh Food off a pile.

Deleting a food building

When a Diner or Grocer is demolished or destroyed, its fresh Food drops as a normal resource pile that drones can carry off, but its Old Food is lost - the Old Food is held in an invisible internal store that has no pile of its own, so it is deleted with the building. (A depot's Old Food, by contrast, is a normal stored resource and drops as a pile like any other.)

When it starts

The rot runs every night from the start of the colony. There is no advance warning and no fixed activation Sol - stored Food can begin ageing as soon as you have Food stored.

What the player is told

The first night any stored Food actually ages into Old Food, a one-off notification "Food Is Now Spoiling" appears. Clicked, it opens the report "Something Is Eating Our Food":

Our biologists have made an unsettling discovery.

A microbe we carried up from Earth has adapted to Mars. In the cold and the thin air it has turned on the one thing we cannot spare, our food. It creeps through sealed crates and the holds of our depots alike.

Our stored Food ages. Each night about a quarter of it turns to Old Food, and about a quarter of the Old Food we already hold rots away to nothing. Old Food still feeds colonists, but it goes on rotting and dwindles the longer it sits. The amount is never the same twice, and it cannot be fully predicted.

Colonists eat the older stock first: at a Diner or Grocer the Old Food is served before any fresh Food. A starving colonist with no Diner or Grocer within reach eats straight from the nearest depot or pile instead, Old Food or fresh alike.

Reserves that once meant safety are now a race against the rot.

How much

Each night, wherever Food is stored, each unit of stored Food has a 25% chance to turn to Old Food, and each unit of stored Old Food has a 25% chance to rot away. Both are a random amount centred on a quarter but different every night: a large amount moves close to a quarter, a small one swings more and can occasionally lose all of it or none. It cannot be predicted exactly.

Legend

• Old Food survives one night before it can rot. The rot step is rolled first each night, on the Old Food that was already in the store. Food that ages tonight becomes Old Food that cannot be lost until the following night at the earliest.
• Food never leaves directly. The only ways a unit of Food leaves a store are being eaten or ageing into Old Food first. There is no path from Food straight to nothing.
• Old Food is its own resource. It is stored, shown and counted separately from Food, and a depot holds both side by side.

Testing

This feature is exercised through the mod's single test mode switch. While it is on, the Food-import ban is lifted (so Food can be imported into a depot), Old Food is orderable from Earth, and every Earth import costs and weighs a tenth. Set it back to off for normal play.

Sources

Survive the Storm mod.
Mod code: mod-survive/Code/StS_FoodSpoilage.lua (the nightly two-step sweep) and mod-survive/Code/StS_OldFood.lua (the Old Food resource); the paired Food-import ban is mod-survive/Code/StS_NoFoodImport.lua.
Old Food is a new resource added by the mod (registered like the resources in _GameConst.lua:148-166). Base-game depot paths used, relative to external/SurvivingMars/Lua: Buildings/StorageDepot.lua:480 (depot add/remove), Buildings/StorageDepot.lua:218-226 (stored / empty storage).