Hello, I recently decided to look back into my old favorite DS game Dragon Quest IX. After doing some digging it seems that there is scant amount of information about the source, or at lease I couldn't find much. I am new to this whole ROM hacking and after spending a few days looking into some things and wanting to try my hand at trying to get some of the internals of this game documented I ran into the problem most do, I guess. Of compressed files. Now finding information on some of these files types has been kind of difficult.
It seems that DQ9 compresses a lot of source files containing a GPC2 header, on .gp2 files. Now from what I gather this is either: 1) something the Nintendo dev kit does for source files, I've seen someone mention it might be multiple LZ compressions run on the same data. Or 2) a custom version of a compression method like a few other games use. Either way, I'm kind of at a loss on how to decompress these files. I've done very little work in hex and even less in this reverse engineering field so I don't really get how I can figure out what format the header of these files is in to create some sort of decompressor.
Another thing I've been trying to find information on is overlay files. DQ9 has 34 overlay files and I feel like there might be something interesting in them. From what I have gathered overlay files on the NDS run some custom assembly before/during(?) game launch. Now the trouble is that overlays seem to use a compression, I have found stuff to decompress them but I don't know what the output file should look like, or what assembly commands the DS even takes. I have found very little documentation on any of this.
Anyways, I'm looking for help getting access to whatever is hiding in these files, mostly for documentation purposes to see how one of my favorite games ran. I've looked all over at what I could find on trying to hack this but I think I've hit my limit on what I can do with little prior experience messing with DS games. The biggest hurdle I think is figuring out these gp2 files, on a really old forum post on another website someone said they could decompress them but I couldn't find any information how, and they gave very little examples.
TL;DR Need everything related to DQ9 rom hacking
It seems that DQ9 compresses a lot of source files containing a GPC2 header, on .gp2 files. Now from what I gather this is either: 1) something the Nintendo dev kit does for source files, I've seen someone mention it might be multiple LZ compressions run on the same data. Or 2) a custom version of a compression method like a few other games use. Either way, I'm kind of at a loss on how to decompress these files. I've done very little work in hex and even less in this reverse engineering field so I don't really get how I can figure out what format the header of these files is in to create some sort of decompressor.
Another thing I've been trying to find information on is overlay files. DQ9 has 34 overlay files and I feel like there might be something interesting in them. From what I have gathered overlay files on the NDS run some custom assembly before/during(?) game launch. Now the trouble is that overlays seem to use a compression, I have found stuff to decompress them but I don't know what the output file should look like, or what assembly commands the DS even takes. I have found very little documentation on any of this.
Anyways, I'm looking for help getting access to whatever is hiding in these files, mostly for documentation purposes to see how one of my favorite games ran. I've looked all over at what I could find on trying to hack this but I think I've hit my limit on what I can do with little prior experience messing with DS games. The biggest hurdle I think is figuring out these gp2 files, on a really old forum post on another website someone said they could decompress them but I couldn't find any information how, and they gave very little examples.
TL;DR Need everything related to DQ9 rom hacking
