Level skip:
Press Start to pause game play, then press Up, Down, Left, Right(2), Left.

Full ammunition:
Press Start to pause game play, then press Left, Right, Left, Right(2), Left.

Invincibility:
Press Start to pause game play, then press Left(2), Right(2), Down, Up.

Refill health:
Press Start to pause game play, then Down(3), Left, Up, Right.

Unlock SegaNet levels:
From the main menu, go to "Network", and click on "Account".
This should switch to "Account 2".
Use the following configuration:

Login name: admin@sega.net
Password: tenages (Seganet spelled backwards)
Area code: Type in your local three digit area code (Ex. 123)
Phone number: Leave blank (do not type in anything)
Primary DNS or DNS1 = 0.0.0.0
Secondary DNS or DNS2 = 0.0.0.0

Click on "Connect" and the game will ask if you want to save changes.
Click on "Yes".
You should now have access to all levels in deathmatch mode
(if you already have completed the game or used the "Level skip" code).
Go to practice and enjoy the two new levels that were previously locked.
Note: Make sure you do this on "Account 2" or your online configuration will be
overwritten -- you will then have to set everything up again.

Glitch: Auto-fire:
When you are playing with two players or more, hold down the fire (or secondary fire) button.
Have another player press the Start button while you are still holding the button down.
When the other player turns off the menu, you will be firing your weapon for as
much ammo as remains.
Press the fire button again to return to normal.

Cheats by Dokta T.; Dokta@Newsring.de