Daikatana

Press the following button combinations at the stage selection screen:
If the code is accepted, you shold hear a sound.

Select any stage:
Press C-Up, C-Right, C-Down, C-Left, R, L, Z, C-Up, C-Right, C-Down, C-Left.

Unlock all weapons:
Press C-Left, C-Down, C-Right, C-Up, Z, L, R, C-Left, C-Down, C-Right, C-Up.