Shadow Man

Play As Deadwing:
Go into the playhouse and get to a room where you see a Cyclops playing pool. Kill it, then jump on the pool table. The "Cheat Active" message appear. Look in the inventory to find the "Book of Shadows". Open the book and "Book of Cheats" will appear at the top. Highlight the "Play as Deadwing" option and press Right. You will now play as Deadwing (or a very big harpie).
Information in this section was contributed by OlDmOlDyGraVy.

Hint: Nettie bleeds:
Go up to Nettie. After she tells a story of your journey or fate, approach and shoot her. To see her bleed, press Snipe then look down at the bottom part of her clothing. You will se a sprinkle of blood coming out of her.
Information in this section was contributed by Powerstone800.

Hint: Getting the first gun:
In order to get the gun in the first place in the game, follow the path. When you reach a dead end, jump on the wall and press Left or Right. When you reach a hole in the wall, press Up. You will now see a dog. Walk to the door and it should open. Walk in and talk to the girl. She will give you a gun. To shoot it, hold C-Up and press Z.
Information in this section was contributed by bad_boy178.

Hint: Continue after credits:
Quickly reach your dead brother for the final battle against Legion and make sure the Trueforms do not move in jails along the last area to the final battle. If you killed Legion with 5 Cadeaux unused, 1 Dark Soul remaining, 1 accumulator and The Book Of Cheats; at the end of the credits you will still be in the game, without Teddy Bear.
Information in this section was contributed by megyno.