Objectives
The game begins with each player voting for one of three core difficulty levels: Normal, Hard, or Insane. Only high-ranked heroes can activate the truly challenging modes of Nightmare and Extinction. Difficulty level scales numerous aspects of the game and determines the requirements of the primary objectives.

In order to win the game, players must successfully complete the primary objectives (in any order) with at least one player's main hero alive. The game ends in defeat if the last surviving main hero dies, even if other support units are still alive. Victorious games award much more experience and unlock rank caps for heroes who hadn't yet beaten the played difficulty level. Completing mini-quests is not necessary to win, but the rewards for doing so may make victory easier to achieve.

Rank 11 is unlocked when a hero has beaten Insane perfectly. To do so requires winning Insane difficulty within 60 minutes with two of the three primary objectives over-achieved and the Hazmat mini-quest completed. A hero advances to Rank 12 when he beats Nightmare mode. To do so requires winning with all three primary objectives over-achieved. Nightmare mode is activated automatically if all players in an Insane game are at least Rank 11.

The hardest difficulty level, Extinction, is activated automatically if all players in an Insane game are Rank 12, and there must be at least two players. Beating it requires winning with all three primary objectives over-achieved and the Hazmat and Red Rads mini-quests completed.

Survival can be selected instead of voting for a core difficulty level. This bonus mode is included for players who simply want to kill stuff. Heroes can earn rank experience in Survival but cannot unlock rank caps. There are no primary objectives in this mode except to stay alive until dawn of Day 3 (44 minutes).

Primary Objectives

Mini-Quests