Type in the cheats menu:
Invincible: NINJA, + 5 000 $: CASHING, All weapons: EQUIP, Always be Kiro: KIRO, Always be Kienji: KIENJI, Always be vinnie: VINNIE, Alawys in rage: RAGE, Unlock next level: NEXT, Weak enemy: WEAK
In this game you will fight as Kiro or Keinji, as you gain new weapons and new combat moves. There's stealth grabs, light and heavy attacks and even the possibility of fight with Kiro and Keniji together. Plenty of bloody fighting and a surprise ending!