Yes, some are very difficult. A main project of mine is Blade Dancer(Dont know why, cause I dont think a lot of people play it since its been out for a while, its rating, and I've already beaten it, but I like the game.), I've made quite an amount of codes for it but a lot of them need adjusting to the users personal prefference and arnt very specific. One main thing is item slot codes I use to subsitute the actual item. So I can tell the item slot how many to have of that item. Well the user has to do some tweaking because if you try to up a slot thats not being used, a useless "None" item will appear that you cant get rid of. I'm able to find the actual adresses of the identity item codes which comes up when I search for the quantity of the item. Well when I try to use the address different from the slot address(which I have a big hunch is the identity adress) the item just flashes numbers. Anyway, I'm babbling once again. My point is I've been working on this for quite a while trying to figure out how to use them as pointer codes to get them to work. If I was able to do that, not only would people not have to worry about the stupid None items, they would be able to put items in there that they dont have yet.
Thats if my hunch is correct though, I'm probaly going to be working on this for quite a while though. Anyway, good luck learning!