At the Press Start screen, hold L + R and press press Up, Up, Down, Up, A, X, A, B, Up, Down, Y, Start.
When you start Peng Lai Lagoon: The Secrets of Peng Lai Lagoon Part 2, go straight forward until you're stopped by a wall, then go to right corner of the wall. There you'll find a DEMO-CHARGE, if you don't find it, move your camera around. Pick up the Demo-Charge, then point yourself to the other corner, and if you look diagonally to the left, you'll see a wall with a crack, go and place your Demo-Charge there. Run away so that you're not damaged by the explosion. When the wall has been blown up, walk trough the hole, and pick up everything in the room. You will find the Panzershreck+Ammo and an Artifact. Just so you know, you can't destroy the big vase in the middle of the room. If you pick up something else, go swimming or use something else, you'll drop it. P.S. This weapon is more fun with the God Mode cheat, 'cause then you fire how many missiles you want.
(supplied by: Swedish Gamer)