Bio Menace Episode Three Secrets

The Bio Menace Series runs on a modified "Good-Bye Galaxy" engine. There are no glitches. It's modified!

If you hold down the keys C, A, and T, then you will get the machine gun with 90 shots, and 99 grenades.
In Guard Tower, at the topo gun turret in the upper-left of the level, get the secret level bonus gem hidden in the wall.
In Utility Maintenance, get the secret level bonus gem in the ceiling above the exit door. In Circle Of Death, get the secret level bonus gem at the floor second down from the top right by jumping up into the roof.
Hold up until you hear a noise. Press "fire." This is a cheat for a plasma bolt. Nice weapon, but it takes one point of damage from Snake.
Turn left and right six or seven times and press "fire." This shoots out six fireballs, three in each direction. I can rarely get this to work, but maybe you will have better luck.
Turn left and right six or seven times and press "JUMP." This gives you an electron shield. If I remember correctly, this makes Snake look like stone and only lasts a second or two. I can't usually get this code to work either.
Hold up until you hear a noise. Press down. You will be invincible for a few seconds.

That's all I know. If you know of another one, e-mail me. I hope you're happy now. Now I have the words "secret level bonus gem" stuck in my head. Secret level bonus gem, secret level bonus gem. . .