Hold [CTRL] In The Main Menu and enter one of the following codes

SKIDMARX   - Enable Cheat and Edit Stats
CREATURE  - Enable Creature Test

Boss Weak Spots
Boss 1: Keep shooting at the red in the left of this Freaks chest. Then when his armor breaks shoot him anywhere on his almost-dead body and hes a dead corpse. Watch out when he goes crazy because he'll keep swinging his Blood-Blade staff.

Boss 2: Keep shooting the Gargoyles stomach til he falls to the ground. Watch out for his bat minions.

Boss 3: Keep Shooting the Giant Spiders face. Just watch out for the webs he throws at you.

Final Boss: This is one tough battle. Keep shooting his handes to reduce the amount of fireballs he throws your way.