Level 8. Zilla's Villa

Start by defeating the initial brown ninjas.

To your right is the silver key door, and to the north is the gold key door. Hit the gong between them to reveal a Ripper Heart.

Take the path left of the gong, go up the stairs, and around to find the GOLD KEY. Defeat the Brown Ninjas and Baby Rippers protecting it.

Return to the gold key door and use the GOLD KEY.

Inside, collect the SILVER KEY, defeat the ripper and guardian, and gather items including rail gun rods and a Riot Gun.

Proceed to the silver key door and use the SILVER KEY.

Enter the room, pick up a gas bomb and night vision goggles from the picture.

Go down the spiral staircase, kill the ninja, and collect shotshells and a flash bomb.

Head to the fireplace for small medikits, then climb the ladder to the roof.

Follow the path on the roof (left, right, left), defeating ninjas until you find the BRONZE KEY.

Pick up the BRONZE KEY and the Rail Gun, then jump down through the opening.

You'll land on the big fireplace. To the left, hitting the gong reveals a hidden area with a missile launcher. The middle door leads to a dojo for health regeneration and sticky bombs. To the right is the bronze key door. Uzi clips are in front of a picture, which also contains a grenade launcher.

Head to the bronze key door and use the BRONZE KEY.

Enter the room, kill the ninjas, and pick up items. Jump to a platform to find the RED KEY and ammo.

Go to the red key door (located in the first fireplace room, behind the silver key door) and use the RED KEY.

Enter the final area, pick up armor and caltrops, and hit the end level switch.