I'm working on a GBA editor and plan to include support for the (J) version (the one used in the PC version). You'll be able to edit some data, more and more as the editor progress. However, even the data from the ROM is not used at 100%, meaning there are some bytes of certain data formats that are simply not used and the feature is governed by tables in the .exe. So what is 100% editable on the GBA might not be the case with the ROM included with the game files. In fact, you could already edit compatible data with FF3usME and copy the hex block to the JAP ROM. A lot of formats are identical on the SNES and GBA version. I'll include as attachment the ROM map I was working on for the (J) version.
As for events, some particular event bytes (identified by their offset) have "hooks" triggered from the .exe to adapt the event to the PC version. I'm uncertain how many there is but Nyxo found a few dozens and by cross-referencing the event dump. It ranges from simple party member / NPC positioning to "cutscenes" triggering (such as the rise of floating continent). It's basically a mess of the basic event layer with a C++ "patching layer" on top.
I also had a look at the .exe, but my understanding of x86 assembly is far from great so there's not much I can do. You can scope out for now a dialogue editor since strings are hardcoded in the .exe. You can also forget for now code changes as nobody except Nyxo really got into understanding the disassembled C++ code. All the combat logic is there so there can't be a bugfix edition until people dive in the code.
I still have hopes for the PC version but realized the Steam community had very few modders and most of its 1500 members were just waiting for patches to come out and weren't even motivated to provide save files to the modders to help testing stuff, which is IMO the basic of the basic.
Topic: The new PC port of FFVI has the GBA ROM in the source code - any modders here? (Read 1448 times)