The ruble (Russian: рубль, rubl') is a form of currency in "The Zone". It is attained from doing jobs or selling items and artifacts. The ruble is given the acronym RU whenever it appears as a value for mission rewards or trading. The ruble was the former currency of the Chernobyl Exclusion Zone prior to the original 1986 incident, and its ubiquity and familiarity caused the Soviet ruble to be adopted as currency in the Zone.

S.T.A.L.K.E.R.: Shadow of Chernobyl

At the start of a new game, the player has 40 RU in their inventory.

Mission Rewards

• Killing the blind dogs attacking Fox after giving him a medkit will be repaid with 1500 RU.
• Repel the bandit raid - 2000 RU, awarded by Bes.
• Meet with Seriy - 2500 RU, awarded by Seriy.

Notes

• For gameplay reasons, cash is not acquired from looting corpses or in stashes. There is however a way to take money from people by selling them items and equipment and leaving them as little money as possible. Then, by killing them, this allows you to recover all sold equipment, plus the other stalker's equipment, whereupon you can repeat the process with another stalker (although weapons sold usually become extremely damaged when you take them back, meaning you will receive less cash for them). If the player does not wish to kill a stalker, he can simply sell him his excess items (medical supplies and ammo are worth much more to other stalkers than they are in stores), which will also allow you to carry more items, as it reduces the amount of weight you are currently carrying (against the carry weight limit).
• Snitch at the 100 Rads bar in Rostok is the only known NPC to refer to the player's currency as "Rubles"; every other time it's shortened to "RU".