DF61-0DDA Start with 2 lives
D461-0DDA Start with 3 lives
D061-0DDA Start with 5 lives
D961-0DDA Start with 6 lives
D561-0DDA Start with 8 lives
DB61-0DDA Start with 10 lives
DD61-0DDA Start with 1 life
DDB2-07A4 Infinite lives
FB83-0D64 Clock runs faster
1083-0D64 Clock runs slower
A683-0D64 Clock runs much slower
DD83-0704 Clock is frozen (no time limit)
DD61-0D0A 1 credit
DF61-0D0A 2 credits
D461-0D0A 3 credits
D761-0D0A 4 credits 
D961-0D0A 6 credits
D561-0D0A 8 credits
EE61-0D0A No credits
C9B9-6D04 Infinite credits
D42B-A7D0 Extra credit after 2 food items instead of 10
D02B-A7D0 Extra credit after 4 food items
D12B-A7D0 Extra credit after 6 food items 
D62B-A7D0 Extra credit after 8 food items
3C2B-A460 Food items never earn extra credit
D184-ADA8 Double harpoon pick-up gives you machine gun
C96E-6FD6 Retain weapon after dying or advancing thru stages
D780-DDD4 + D781-DF04 Panic mode has 2 levels instead of 99
D180-DDD4 + D181-DF04 Panic mode has 5 levels
D880-DDD4 + D881-DF04 Panic mode has 10 levels
F980-DDD4 + F981-DF04 Panic mode has 20 levels