Maken X Cheat Codes for Dreamcast

All weapons
Pause the game, and then press: Up, Right, Left, Down, B, L, R, A, Right, X, B, Left, R, Y, Up.

Full pause screen
As with most other Dreamcast games, hit X+Y at the pause screen to remove the menus from view.

Invincibility
Pause the game, and then press: Down, Left, Up, Right, L, A, X, Left, R, B, Y, Up, L, A, Down.