Kinda late, but it was Zetsubou No Shima. Completed on round 28. First run at the easter egg, I thought it would have been a more complicated battle.
Call of Duty Zombies (CODZ) is a fan-managed gaming community centered around the popular Call of Duty franchise with central focus on the Zombies mode. Created in 2009, CoDZ is the ultimate platform for discussing Zombies theories, strategies, and connecting players.