Collect all weapons in the campaign.

Withstand the zombie siege.

Complete the game with an S rank.

Complete the game on "Standard" or higher.

Complete the game with an S rank on "Inferno."

Gather all the fuses in the warehouse within 5 minutes.

Complete the game on "Nightmare" or higher.

Defeat Stage 2 Nemesis.

Complete the game using 1 or fewer recovery items.

Complete the game with an S rank on "Inferno."

In Spaceland, Pack-A-Punch a weapon.

Reach level 50.

Borrow 10 books.