A Hirogen Klingon simulation was a holoprogram ran by the Hirogen on USS Voyager's holodeck two after they took over the ship for several weeks in 2374. They used the holodecks to hunt Voyager crew as prey, as to explore a new way for their culture to exist. Crew deployed there were altered to look like Klingons.
Kathryn Janeway, served as an interactive character belonging to the House of Mo'Kai. She battled several other Klingons before being stabbed by a Hirogen and being taken out for medical treatment. Afterwards, she was transferred to a World War II simulation that was being started up. Later, Neelix was transferred from the World War II simulation to the Klingon simulation.
The Klingons from this simulation were later convinced to fight against the Nazis in the Sainte Claire holoprogram, aiding the Voyager crew in their fight to take the ship back from the Hirogen. (VOY: "The Killing Game", "The Killing Game, Part II")