FE8 editing - desert items and some other queries

[Tables]

I'm currently trying to make a difficulty mod for FE8, with my limited hacking skill (mostly I know Nightmare fairly well and that's about it). So far I haven't had too much problem with what I'm trying to do - there's a few things I'd like to do but haven't been able because either it'd be too complicated or just not feasible in any reasonable timeframe. But one thing that I thought might well be easy enough to do is editing items in the desert, and possibly other items from events and houses. In particular I'd like to change the chapter 15 Warp Staff and Silver Card into other items, most likely a Fortify and some kind of gem respectively. Could anyone give me some advice on how these could be done?

Other things I have been considering changing are the EXP formula (this seems likely unfeasible), and editing enemy starting locations, reinforcements and possibly adding more enemies onto chapters. Doing this requires I think a better understanding of how the enemy location data works - I've tried fiddling with the X and Y fields in Nightmare before and always come up blank on how that works (except that if the Y co-ordinate is greater than 32 (mod 64) the enemy drops an item when killed, which is, uh, interesting). And to add more enemies into chapters, I'd have to have some idea of how to place them where I want, so... yeah. And also know where in the data I can and should add extra enemies, I suppose.

One more question for now: Does anyone know how monster data is generated for random encounters like skirmishes and things like the Tower/Ruins? From what I can tell with a light peek in, the monsters 'class' actually gives a list of possible classes, e.g. 0x01 (Eirika Lord) could potentially become a Mauthe Doog, Revenant, Entombed or either Bonewalker, and possibly others. Level also seems to be slightly randomised. If anyone has extra details (especially documenting what each class corresponds to) that'd be great.

Thanks for any help anyone can give.

[SquareRootOfPi]

Most of what you want to do can be accomplished by editing events, e.g. desert drops and changing enemy spawns. Have you tried disassembling and editing events?

FE8 stores X,Y coordinates differently from other GBA games. Instead of storing it as a byte pair it stores it as an array index. I believe the array is the map unraveled by rows, so if a map is AxB large then x,y is stored as A*y+x and the format is a halfword (0xNNMM); so the NN portion would be saved as the Y-coordinate and the MM portion would be saved as the X-coordinate. A concrete example: If you have a map that's 23x24, and you want to place an enemy at 6,19, the data to be stored is 19*23 + 6, which is 0x01BB as a hex value. So you want to save 0xBB as the X-coordinate in and 0x1 as the Y-coordinate. This is based off vague recollections so there might be something wrong with the specific details, you'll need to do some checking to see if it fits with the existing data.

There is a limit to how large the map array is (I think the maximum index it can save is 0xFFF, the size of a 64x64 map) so whatever isn't used is used to store additional information about units.

[Tables]

I've never done anything with event editing, but I might look into it.

Thanks for that information on co-ordinate storage. I think the basic idea should be enough for me to decipher where units are located and how to move them around.

[Vennobennu]

Note that disassembled events in Event Assembler displays the coordinates in their simple form, ie [XX,YY], so there's one advantage to using EA.

For desert items in particular, the identity of the item to be given is defined in a _SETVAL command, so look for those.