The Endurance System is an essential feature in Underhell. Jake will get hungry and/or thirsty during the course of the game if he doesn't eat or drink for prolonged periods. When the meter is nearly or completely full (blue), Jake's stamina will refresh very quickly and he will even slowly regain any lost hitpoints. As the meter decreases, so does his stamina regeneration rate, and he will no longer recover health over time.
- This feature is possibly based on the hunger system from the S.T.A.L.K.E.R. video games.