Alternate Cynthia costume:
Unlock all 4 endings and Eileen's alternate costume, all on 1 saved game. Start a new game and choose Eileen's alternate costume. Cynthia will then wear her alternate costume.

Brand New Fear mode:
After completing the game. Save the game after the credits. This will unlock the "Brand New Fear" option.

Eileen Nurse outfit:
Start a new game using that a finished saved game and go to room 302 to find Eileen's nurse wear, it can be picked up on the 3rd time through.

Chainsaw:
Reload the finished saved game and then the go to forest world and look for the cut tree, you'll see the chainsaw near there.

Submachine Gun:
Successfully complete the game with a rank of at least 9 big stars. Start a game in "Brand New Fear" mode and look in Room 202 in the Apartment World.

Unlock One weapon:
Get 10 stars using hard mode

Unlock all weapons:
Finish one weapon mode