Shadow Man

Obtaining the Book Of Shadows:
Go to Deadside: Marrow Gates. At the beginning of the level, go to the left and climb up the blood waterfall. Open up the Shadow level 10 Coffin Gate (120 Dark Souls). Along with a "Thank You", you will be able to see pictures drawn during the game's development.
Information in this section was contributed by Mark Porga.

Deadside shotguns:
Go to the Wasteland and enter the Temple Of Life. Walk into the second to last altar on the right, where you get the Baton and press B. The "Secret Activated" message will appear.
Information in this section was contributed by Mark Porga.

Pea Soup mode:
Go to the Temple Of Fire. Locate the pool of blood and find the door that leads to a room with a ramp going up the left that leads another ramp. Move up the ramp and look to the left to see a hallway. Jump on the railing and jump towards the hallway. You should grab the ledge in front of it. Pull yourself up. The "Secret Activated" message should appear.
Information in this section was contributed by Jed the Head.

Play as Bloodshot:
Go to the Temple Of Blood (Nager) and enter the small bonus room reached from the platform that is knocked down by the large hammer. The "Secret Activated" message will appear when you walk in the room.
Information in this section was contributed by Mark Porga and Dale.

Play as Deadwing:
Go to Gardelle county jail and find the maximum security cells (the small red rooms lined up in a row). Go inside the one on the lower floor on the left, farthest to the right.
Information in this section was contributed by Mark Porga.

Play as Duppie:
Go to the Undercity. Go to the ledge where two snipers are awaiting your disposal. Jump to the ledge on the right, climb onto the next ledge, and look for the curved U-shaped pipe. Jump to it and the "Secret Activated" message will appear.
Information in this section was contributed by Mark Porga.

Play as Nettie:
Go to the Mordant St. NY. Follow the paths until reaching a room with a lever. Pull the lever and the lights will turn on. Enter the elevator and go up. Go find the door, then look for a brown patch on the floor. Jump as far as possible, then jump again. If you are quick enough you will get over and the "Secret Activated" message will appear. If you fall through, use the bear to warp there and try again.
Information in this section was contributed by Jed the Head.

Play as a dog:
Go to the Asylum: Gateway and go to the path before the door on the left under the bridge. Follow it until find a room with a Govi and some boxes. Climb the boxes and jump on the rafters. Jump to the second rafter, then jump to the third rafter. The "Secret Activated" message will appear.
Information in this section was contributed by Jed the Head.

Flame on mode:
Go to Dr. Death's Schism Gate and go to where you fight the helicopter and destroy it. Then, go to the tunnel to the right of the entrance. The "Secret Activated" message will appear. Note: The gate should not be opened before unlocking the secret.
Information in this section was contributed by Mark Porga.

Big head mode:
Warp to Asylum: Playrooms. Go to where the playroom cells are found (with a pool table and a playpen). Enter one of the empty cells and roam around until the "Secret Activated" message appears.
Information in this section was contributed by FoIIowTheKoRn.

Comedy shoes:
Go to Deadside: Marrow Gates. At the beginning of the level, go to the left and climb up the blood waterfall. Go through the Shadow level 10 Coffin Gate and the "Secret Activated" message will appear.
Information in this section was contributed by Mark Porga.

Invisible man:
Go to London Underground via Jack The Ripper. Go to the middle stall in the women's bathroom and the "Secret Activated" message will appear
Information in this section was contributed by Mark Porga.

Disco mode:
Go to the Cathedral Of Pain and drop down the shaft into the Marcher lava. Go on the top of the spinning blades, then find your way to another shaft that goes down. Drop down and the "Secret Activated" message will appear as you fall.
Information in this section was contributed by Mark Porga.

Shotgun head mode:
Go to Temple of Prophecy (Marcher) and enter the "Flambeau maze". Find your way to the center of the room on the ground level and the "Secret Activated" message will appear.
Information in this section was contributed by Mark Porga.

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.