Cheat Codes:

A cheat to get heaps of oil credit in KKND or KKND Xtreme.
Begin a level and then save the game.

Use a hex editor eg. XTGOLD

In XTGOLD highlight the saved file and then press V for view, H for Hex, E for edit. After you have edited the hex press enter, Esc and quit XTGOLD. Now go back to KKND/KKND Xtreme and restart your saved game. 

In the Survivors levels the first line of your hex will look something like this:- 

000000 0100 0000 0000 0000 0000 0000 0000 0000

Regardless of the numbers that may be in your saved game change this to: 

000000 0100 0000 0000 0000 F301 F301 F301 0000

This will give you over 32 million oil credits.

In the Mutants levels your hex will look something like this:- 

000000 0200 0000 0000 0000 0000 0000 0000 0000

Change this to:

000000 0200 0000 0000 0000 0000 FFFF FFFF FFFF

This will give you a negative oil figure with the result that you will never run out of oil credits.