Unlockable Characters:

To unlock extra characters, complete the requirements and buy them from the Costumes area of the collection screen. 

Peter: Beat the "Decisions, Decisions" Scenario on Hard Mode.

Greg: Beat the "Decisions, Decisions" Scenario on Very Hard Mode.

Fireman: Beat the "Hellfire" Scenario.

Frank: Beat the "Decisions, Decisions" Scenario with George.

Monica: Beat the "Below Freezing Point" Scenario with Yoko.

Yoko D: Beat "Outbreak" with Yoko.

Bob: Beat "Outbreak" with Mark.

Will: Beat "Outbreak" on Very Hard Mode.

Unlockable Hard Mode:

Beat all Scenarios once.

Unlockable Infinite Ammo:

To make the infinite ammo mode purchasable in the shop, get 100% completion in all scenarios.

Unlockable No Partner Mode:

Beat all Scenarios once in Hard Mode.

Unlockable Very Hard Mode:

Beat all Scenarios once in Hard Mode.

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