Base

The Base is presumably the main residence of Johnny Trigger. There are nine visible floors (and one secret floor) to be unlocked. Each floor needs keys to be unlocked and hammers to be completed. Once completed you'll get a Base Gun and a Base Outfit.

= List of floors =

The Apartment
The Apartment is the first floor unlocked. To complete it you need 45 hammers.

Unlocked Items:

 * Suit-2 (outfit)
 * Silenced (gun)

Planning Ground
You need three keys to unlock the second floor.