ROM Hack Hacking a GBA rom (Sonic Battle)

[Metoroid0]

Hi guys!
I was wondering, will you help me to figure out how i can hack sonic battle game for GBA.

What i want to do is to replace rouges sprites with other sprite character that are custom made for sonic battle. You know, to replace all rouges animations with that other character, not just changing color pallet.

Can you help me find the tools and give me some advices if you have experience?

Thank you in advance.

 

[FAST6191]

I seem to recall this was a kind of isometric/3d game and on the GBA that can be fun. However I watched a let's play of it and it seems it is mostly spritework in a 3d world a la doom and duke nukem 3d so you will hopefully be just doing conventional GBA 2d editing -- I was taking a look at super monkey ball the other month and if this was like that you would not want this to be your first GBA hacking experience.

Anyway I cover quite a bit of graphics work in the hacking docs in the DS ROM hacking section http://gbatemp.net/threads/gbatemp-rom-hacking-documentation-project-new-2014-edition-out.73394/
Step one would be fine a tile editor ( http://filetrip.net/nds-downloads/utilities/download-crystaltile2-2010-09-06-f23649.html and http://home.arcor.de/minako.aino/TilEd2002/ would be my first ports of call)
Have a look through the ROM with those and hopefully you can find something, if that does not get what you need then after that you will have to start thinking about hacking proper (possibly dealing with compression, doing things like http://www.romhacking.net/documents/361/ and more involved methods of finding things.

 

[Metoroid0]

I seem to recall this was a kind of isometric/3d game and on the GBA that can be fun. However I watched a let's play of it and it seems it is mostly spritework in a 3d world a la doom and duke nukem 3d so you will hopefully be just doing conventional GBA 2d editing -- I was taking a look at super monkey ball the other month and if this was like that you would not want this to be your first GBA hacking experience.

Anyway I cover quite a bit of graphics work in the hacking docs in the DS ROM hacking section http://gbatemp.net/threads/gbatemp-rom-hacking-documentation-project-new-2014-edition-out.73394/
Step one would be fine a tile editor ( http://filetrip.net/nds-downloads/utilities/download-crystaltile2-2010-09-06-f23649.html and http://home.arcor.de/minako.aino/TilEd2002/ would be my first ports of call)
Have a look through the ROM with those and hopefully you can find something, if that does not get what you need then after that you will have to start thinking about hacking proper (possibly dealing with compression, doing things like http://www.romhacking.net/documents/361/ and more involved methods of finding things.

Thank you. So the first thing you say is to find those sprites i want to replace in rom it self, in its code, but since some are compressed, i need to learn to uncompress them...?

 

[FAST6191]

I do not know if any are compressed as I have not looked at the ROM yet. That was more an if they are compressed, though I should say there are tools (covered in the guide I linked) that will search for compressed stuff that is compressed in a common way (most things are on the GBA but not all) and try to decompress it.

 

[Metoroid0]

How would i know if they are compressed..lets say i open and i say "aha that is compressed file!" ?

 

[FAST6191]

There are ways you can tell, mostly though if you scan through the ROM using a tile editor and can not see it then it is probably compressed -- on a PC it might instead be in a format you do not know or encrypted but the GBA tends to stick close to the hardware and does not encrypt.

 

[Metoroid0]

I noticed (when i opened sonic battle in TileED 2002 and in CrystalTile2) that there is a lot of gibberish sprite like dots, like a lot of them, than as i scrolled down i noticed tails, sonic etc, but in inverted colors, and little offset, like legs are not in line with a body...