Enter the password BVGGY to open up the Cheat Menu Option. You can skip levels, view FMV's and adjust your power level and number of lives.

Any time the monster tries to get shot by any force from the military, the shot deflects back
to it.

M1UY0

Enter these passwords to play as the following characters:

Ralph / LVPVS
George / SM14N
Lizzy / S4VRS
Myukus / NOT3T
Myukus 2 / B1G4L
Noob / SRY3D

It's interesting to note that the passwords describe the character they unlock somewhat.
For instance, Ralph is a wolf, and the scientific term for wolf-like is Lupine, thus the password translates to Lupus. George is a gorilla, thus Simian. Lizzy translates as Saurus. Myukus is humorously enough, Not E.T.