Sustenance System

Baseline

Energy (EP): 12 points, you lose 2 per day.
Water (WP): 6 points, you lose 2 per day.

All food has an EP value.
A canteen is considered to have a whole water point.

Exertion

Strenuous exertion will make you consume more EP and HP than usual. For instance, when you'll enter combat, you will start secreting adrenalin. You will experience vasodilation, your body will start pumping blood and sugar into your muscles, your body temperature will raise, and you will start sweating to cool off.

• Climbing: Over 60 m in altitude. 1 WP, 1 EP.
• Long distance jogging: Over 3 km. 1 WP, 1 EP.
• Fast Sprinting: Over 100 m. 1 WP, 1 EP.
• Long Combat: Each 4 rounds. 1 WP, 1 EP.

These are cumulative.
If you fight for 8 rounds, you will spend 2 WP and 2 EP.
If you fight 4 rounds and then flee by fast sprinting 200 m, you will lose 3 WP, and 3 EP.

Temperature and Climate

Harsh climatic conditions might also make you consume more than normal.

• Cold: Below 0°C, 12 hours. 1 extra EP.
• Heat: Above 35°C, 12 hours. 1 extra WP.

These are cumulative. 24 hours above 35°C will make you spend 2 WP, in addition to your baseline 2 WP consumption.
Exertion and climatic conditions are also cumulative.

Some of these effects can be bypassed or reduced through mutations, equipment, potions, substance consumption, etc.

Starvation and Thirst

If you reach nightfall with 4 WP, or less, you are Thirsty.
If you reach nightfall with 8 EP, or less, you are Starved.
If you are either Thirsty or Starved at nightfall, you need to roll Vigor. If you succeed nothing happens, but if you fail, you get 1 Fatigue level. On a Critical Failure you get 2 Fatigue Levels.
Fatigue Levels lost by Thirst or Starvation can only be recovered by ingesting enough water or food, respectively.
To start recovering Fatigue Levels you got due to Thirst, you must reach at least 5 WP.
To start recovering Fatigue Levels you got due to Starvation, you must reach at least 9 EP.
If you drop to zero WP you are Dying of Thirst.
If you drop to zero EP you are Dying of Starvation.
From the moment you are considered Dying of Thirst or Starvation, you start suffering 1 Fatigue Level per hour.
To stop this, you must ingest at least 1 WP worth of water if you are Dying of Thirst, or 1 EP worth of Food if you are Dying of Starvation.
If you get Incapacitated due to Thirst or Starvation you cannot move by yourself, and you'll die after 24 hours, unless someone else provides food if you are starving, or water if you are thirsty.