Ultimatum is a group of stalkers from the Mercenary Ghost modification. They are known as fighters for justice in the Zone, who destroy mutants and "dirty people" of the Zone. They look like Debt, besides, according to rumors, their group was founded by former debtors. One of their main goals of the group is to eliminate the man known as the atomic stalker, who killed more than a thousand people in the Zone. Also, all members of this group are well equipped. They have their own armored suits and exoskeletons, created on the basis of stalkers.