No Death Code  -  In the options screen under the password field, enter XBABYX and it will say CORRECT. The code makes it so even when your life runs out, you will not die.

Level Select from Matt  -  In the options screen under the password field, enter ZZZCYX for a level select. 

Rapid Fire  -  YAYAYA - in the options screen under the password field. 

Level Passwords  -  level 2-2-CBYXYC 3-1-XABXAB 3-2-AZCBXC 4-1-YYBBCY 4-2-BAXCXX 

New level from QSun  -  In level 2 go to the map and look down until you see 3 bumps. Go to the closest bump to the real exit sign. There behind a gun turrent, you will find anther exit sign. After entering it you will get anther mission full of power, guns, shields, bombs, both kinds of missiles, and hull.