Hybrid Heaven cheats and cheat codes for Nintendo 64

Finish the game in ultimate difficulty level. The go to the title screen
and enter the following codes to unlock characters and new mode.
Note: If the codes are accepted, you should hear a sound.

Unlock Extra mode: Press L, R, L, R, A.
Play as an alien: Press L, R, L, R, Z.
Play as President Weller: Press L, R, L, R, Start.