All Working Earthworm Jim 3D Cheats - Nintendo 64

Level select
Pause game play and press [Right], [R], [B], [A], [L]x2, [A], [R].

Small Jim
Hold [Z] and press [C-Up], [C-Down], [Left] at the title screen, then begin game play.

Unlimited lives
Go outside the entrance to "Hungry Tonight?" Collect the Power Parp Tin from Snott and use it to collect the nearby extra life. Enter "Hungry Tonight?" and immediately exit. Talk to Snott again to get another Power Parp Tin, then collect the extra life again. Repeat this to get as many extra lives as needed.

Defeating Fatty Roswell
Collect two of the three missiles and wait at the third. He will teleport there and be an easy target.

Defeating Psycrow
Ignore the marbles, collect bullets at all times, and shoot him. Keep his marble level at 0 or close to it at all times. This will allow you to get your marble level up to approximately 85 within a few minutes.

The Good, the Bad, and the Elderly: