if there is a key to encrypt it , it can be decrypted , same with a few more games that use this method , some crytek games also.
find the key , reverse the encryption ( usually a long string like JPE521JOZ57E4TFA9AX3 ) etc , then get the tea and pour in the milk and sugar , sit back and change anything you wish.
search file name
breakpoint
find what access it and why ( usually read decrypt / encrypt and write on 99% )
intercept
hack away.
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or another easy attack method for encryption is to intercept the actual read value routine , check for what it is you wish to change and ... change it.
eg
MEMORYAD = strstr (isit,"s1mple=");
strncpy (MEMORYAD,"s1mple=100000",13);
or
cmp word [eax],"s1mp" ;( pseudo )
other methods work too many to mention.