Abadox:

#1.  Invincibility

Input this at the Credit screen where it tells you to press start.  

The code is A, A, UP, B, B, DOWN, A, B, START.  

#2.  Stage Select Code 

Input this quickly at the Credit screen where it tells you to press start.  

The code is LEFT, UP, RIGHT, DOWN, UP, RIGHT, LEFT, DOWN and then press one of these buttons to take you to the corresponding stage:
 
Stage 2:  UP

Stage 3:  LEFT

Stage 4:  DOWN

Stage 5:  RIGHT

Stage 6:  SELECT

Stage 7:  B

Cheats sent in by Kevin Miller.
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