Dark Sector is an action game where you play as Hayden Tenno , a top-secret agent sent to destroy a deadly virus in Lasria, a small USSR country. The goal is to stop the virus from turning people into mutants and find its creator, Mezner.
The mission takes a personal turn when Hayden discovers Mezner and gets infected with the virus himself. This mutation gives him new abilities, such as invisibility, shields, and the glaive - a special knife-like weapon that can be used in both close combat and long-range attacks.
Hayden can also use conventional firearms like shotguns or pistols, which can be picked up from enemies or bought from the Black Market. These guns can be modified to suit his needs.
The game features a multiplayer mode with two options: Infection, where one player is a fully mutated Hayden and the others must hunt them down as ordinary soldiers, and Epidemic, where two teams compete to kill each other's mutants.