To get the ten Birdskulls, you must first have the assassin's rifle. After getting the assault rifle, go to the beginning of the path that leads you to Netti's church. You will see a hut. Turn right and you should see another hut that has/had a Cadeaux in it. Go around it and you will see lots of barrels. Back up slightly and shoot them from a safe distance with the assassin's rifle. A path will open. Follow the path until you reach a lake with birds flying around and a few crocodiles. Kill the crocodiles before going any further. The birds flying around carry the Birdskulls (one each). Kill ten of them. Note: One of the birds only flies around once in a while so it is difficulty to kill it. Every bird that you kill in this area will drop a birdskull into the water. You must swim to get it. The birdskulls never disappear. In the event that they drop one on a boat, forget about it : you cannot go on top of them. If this happens the game will send you an extra bird.
Cadeaux
When trying to get the second Sigil in Gehenna, instead of trying to balance on the wall to cross the room, just pull the switch to raise the wall sections. Then, wait near the switch for the walls to descend. While the wall is descending, wait for it to be low enough to jump on and quickly jump to the higher platform. Pull the switch there to raise a ladder, then use this ladder after pulling the switch again to get the second Cadeaux.
Use the following trick in the Gehenna Sigil chambers where the thin platforms (walls) rise and you have only 20 seconds to do it. Pull the lever to make the walls rise, then go up the ladder. Walk on the ledge to the first alcove with the Cadeaux in it. Take your time. When you get it, go back to the lever. Pull the lever and take five to six steps backwards align Shadow Man with the wall near the lever. When the walls start to descend, get ready. When the walls reach Shadow Man's height, run and jump then jump again. You will be able to grab on the ledge. Pull yourself up then pull the lever to make the ladder appear. Then, go back down again and pull the lever to make the walls rise again. Go up the new ladder and walk to the second alcove. Jump and grab the second Cadeaux. The same thing is done for the next level with rising walls (platforms).
Control loading screen
Rotate the Left Analog-stick at the loading screen to make the words and the fire in the background move around. Press L or R to make the screen change colors and have other effects.
Defeating most enemies and Bosses
Circle around the enemy or Boss by pressing either Left on both Analog-sticks or Right on both Analog-sticks. This will make you surround the enemy or boss while keeping your view on it. Then, shoot them with any weapon. If it flies press Right Analog-stick Down slightly, so you can watch it while it flies.
Game Shark Codes
Master Code (Must Be On)
0E3C7DF2 1853E59E
EE81C256 BCC80902
Black Sabbath Video Mode [Note 2]
FE93385D BCA99B82
FE93385F BCA99B82
Note 1: Hold X to jump higher. Also, if you jump too high you will fall through floor when you land, so make sure to save often.
Note 2: Do not use these codes together.
Nephilim Shard
The Nephilim Shard is given to you by Duncan the first time you see him; immediately after you find Jaunty and the ten bird skulls.
Run backwards
After you have the Watch and the Sniper Rifle, look through the sight then press Select. Get the Watch and switch to Shadowman or Mike. As you are transforming, holster your weapons. Your sight is still there. Press "Reset Camera" or you will run backwards.
Shadow Gun and watch
You find the Shadow Gun and Mike's watch in the sepulcher, which is where Duncan sends you. It takes a while until you get there.