In the game, the building unlocks when the player has finished the game once and begins a new game in EX game mode.
The Chrysler Building test allows the player the chance to save only every ten floors and only after defeating a boss. The items, weapons, power-ups and enemies are of a higher class. The best items, armors, and weapons are here along with the trading cards that allow the player to make customizations to the weapons and get the tool and super-tool kits. It should also be noted that every floor, except floors 1, 10, 20, 30, 40, 50, 60, 70-77, are completely randomized so each floor is like a maze.
Most enemies and bosses encountered are similar to those from the main game, like the Golden Rat, Alligator, Triceratops and giant Centipede, but new monsters such as giant Squirrels, giant Cockroaches, and Queen Bee can also be found. The boss in the last floor of the building floor 77 is the true final boss of the game and it has the form of Aya Brea's deceased sister, Maya.
The boss of each floor are:
- 10th floor: Spiderwoman
- 20th floor: Alligator (2x)
- 30th floor: Centipede
- 40th floor: Triceratops
- 50th floor: Cockroach (2x)
- 60th floor: Crab
- 70th floor: Bee (x3)
- 77th floor: Truebred Eve
The final boss explains to Aya that Dr. Hans Klamp cultivated the cells of the original Eve to analyze. When Melissa Pearce was giving birth to the Ultimate Being, she created a nest there. In case Melissa and the Utimate Being failed, the purebred would still remain. Aya speaks with her sister, and they engage in battle against the purebred. The purebred has taken Aya's Liberate form and can use attacks similar to Aya and more.
After the purebred is defeated, the mitochondria inside Aya begin to rebel against her. The explanation is that Aya's mitochondria have now reached a higher evolutionary stage than Maya's, but Maya's personality has suddenly become dominant and begun to fight off the Eve persona. Maya eventually wins, purging the Eve persona from herself and protects Aya by preventing the original Eve from taking over her. Aya leaves the building by herself, although she apparently has gained some sort of connection with her dead sister. Maya's body is not physically present in either scenario, only Eve is. What actually happens is arguable due to the scene's lack of camera angles for certain characters.
|Aya Brea - Daniel Dollis - Kunihiko Maeda - Melissa Pearce - Mitochondria Eve|
Maya Brea - Ben Dollis - Lorraine Dollis - Hans Klamp - Douglas Baker - Torres Owens - Wayne Garcia
|Armadillo - Bacterium - Bat - Bear - Cat - Centipede - Chameleon - Crow - Dogman - Flyman - Frog - Mixedman - Mole - Monkey - Parrot - Plant - Pterodactyl - Rat - Ratman - Spider - Scorpion - Squirrel - Snake - Treasurebox - Troodon|
|Alligator - Bee - Cockroach - Crab - Eve - Giantworm - Kerberos - Spiderwoman - Triceratops - Truebred Eve - T-Rex - Ultimate Being|
|American Museum of Natural History - Carnegie Hall - Central Park - Chinatown - Chrysler Building - N.Y.P.D. - Soho - St. Francis Hospital - Subway - Warehouse|
|Weapons - Soundtrack - Remixes Soundtrack|