Punisher, the Cheats

To beat Bullseye you have to stun him with grenades to reduce his health
and shoot him in the bullseye on his forehead to finish him.  Just
spraying bullets at his armor is a waste of time.

To Unlock Everything
Enter the profile 'V PIRATE' (in all caps) to unlock everything in the game. The following cheats are under extras:
Invulnerability
One Shot, One Kill
Gun Splitters
Cray Deaths
Crazy Deaths
No Reload
Unlimited Aammo
Unlimited slaughter Mode
Unlock
To unlock a cheat you must get a Gold medal on the indicated level:

Crazy Deaths:
Lucky's Bar Level

Gun Splitters:
Crack House Level

One Shot Kills:
Ryker's Island Level

Invincibility:
Every Level

No Reloads:
Stark Towers
Unlimited Ammo:
Pier 74 Revisited

Unlock Infinite Slaughter Mode
Get a Gold medal on the Taikagi Level (2nd last level) and receive infinite Slaughter Mode.
Unlock Machine Gun:
Beat Grey's Funeral Home Level
Unlock 5.7mm Submachine Gun:
Beat Fisk Industries level

Unlock Machine Pistol .45 cal:
Beat Chop Shop Level

Unlock Machine Pistol 5.56mm:
Beat Grey's Funeral Home Level

Unlock Revolver:
Beat Lucky's Bar Level

Unlock Sniper Rifle:
Beat Grand Nixon Island level
Unlock 5.56mm Assault Rifle:
Beat Central Zoo Level

Unlock Auto Shotgun:
Beat Takagi Building Level

Unlock Battle Rifle:
Beat Stark Towers Level

Unlock .40 cal Submachine Gun:
Beat Gnucci Estate level
Unlock Hand Cannon:
Beat Gnucci Level
Unlock .50 cal Semi-automatic Pistol:
Beat Igor Baltiysky level
Unlock Flame Thrower:
Beat Igor Baltiysky level
Unlock 7.62mm Assault Rifle:
Beat Pier 74 Level
Unlock Grenade Launcher:
Beat Pier 74 level

Unlock Anti-tank Weapon:
Beat Pier 74 Revisited level

Create a profile with the name "V Pirate" to unlock everything except for upgrades.

To achieve a high score, grab a human shield and use him. Shoot some enemies and try not to get hit. The longer you go without getting hit, the higher your points get. However, if you somehow get hit your points are rounded up and you must start again with not getting hit.

Get a gold medal on the Taikagi Level (2nd last level) and receive infinite slaughter mode.

The first guard you encounter in Ryker's will be held up by a prisoner. The prisoner refers to him by the name "Dixon". He is named after Chuck Dixon, a writer for the Punisher comics, Daredevil comics, and Marvel Knights comics.