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PostPosted: Fri Feb 24, 2017 11:24 pm 
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Hi,

Can you tell me how a coder can import levels from an old NES game and then create an .nes file? The last freelance programmer I spoke with said they need source data - which I now understand to be unavailable (engineered in assembly only). But, Ive seen games modded into, and I know there must be some way it is done weather debugging in Nintendulator or FCEUX.

a) I've been told about logging writes to nametables during emulation in each level to enable nametable data to then be built.
b) Another option was to look in VRAM to see graphics in the game and then mod from there with a knowledgeable coder.
c) A third option was vgmaps.com, which led me down a flash game route...which inspired me to learn myself, but now I've found that will not translate into an NES game. Unless the .swf can be made into a video file perhaps and then converted, but I don;t think so.
c+) or, write an importer program that recognizes tiles from the image maps and imports them that way.
d) Yet another is offered by a new coder offering to do my game in level creator...of which program, and how it'll turn into a .nes file...I don't know.
e) the game needs to be done via reverse engineering in 6502; basically a very long process as I understand, and from scratch.
f) -this is difficult lol ...any other suggestions??

I'm not a coder and never will be...just need to know what to ask potential coders to ensure they are qualified to take on the project.
Or, if someone can try one of the options like debugging the orig. game through emulator or whatever, it'd be very much appreciated.

Thanks for reading, any solid help would be awesome!


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PostPosted: Sat Feb 25, 2017 12:04 am 
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Would you say you are trying to, more or less, hack an existing game, changing certain aspects of it (graphics, music, level layout) or are you trying to create an entirely original game?

Because creating a homebrew requires much more intricate knowledge compared to hacking (reverse engineering), at least based on my experience.

Is there a specific game you had in mind?

(Keep in mind, existing games have been hacked into completely new games: http://www.romhacking.net/forum/index.p ... 418.0.html

...so that might be a feasible route.)

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PostPosted: Sat Feb 25, 2017 12:44 am 
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hey, thanks for your reply ;)

yeah, what I want to do is import most of the game levels actions, etc and then just change items plus add bmps to backgrounds and music files to make it a modded game. So, hack sounded fine, yeah..but I'm being told by some that only way to go is homebrew because the original source code is unavailable and emulators/ debugging doesn't help? Only 6502. But then, how are SMB3 hacks, etc. done as mods?

thanks, though...starting to think there me be hope...many hours of research here and misled by 2 coders already....if your suggestion doesn't work, I guess I could make it in flash and play with an SNES controller w/ USB hookup.

btw, anyone feel free to pm any ideas or proposals that involve coding...Ideally, this will be an .nes rom file that will make it to an actual game cart. Its for my kids, they made most changes. Thanks a lot ;)


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PostPosted: Sat Feb 25, 2017 12:44 am 
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sorry I pm'ed that general reply btw....still new to this forum.


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PostPosted: Sat Feb 25, 2017 2:28 am 
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Simple hacks (graphics, palettes) are possible after a little bit of research, but more extensive modding (adding new moves, new objects, etc.) requires a much deeper knowledge of the game's engine.

There are programmers who go through the trouble of disassembling the games and reverse engineering all the logic to create something that resembles source code, with named variables and labels, comments, and so on. When done right, these disassemblies can be more easily understood by other programmers, modified, and assembled back into a binary ROM. Making a comprehensive reassemblable disassembly is A LOT of work though, so you don't see these in the wild very often.


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PostPosted: Sat Feb 25, 2017 3:01 am 
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Don't mean to derail the thread, but are you the guy who posted this ad on freelancer?

https://m.freelancer.com/projects/gerri_13108878.html

It would help a lot if you could mention the game you want to mod. A few games are very well understood (Mario, Castlevania) and that completely changes how hard the job is.

Quote:
add bmps to backgrounds

Depending on the BMP files you want to add this may very well be impossible. The NES is pretty restrictive.


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PostPosted: Sat Feb 25, 2017 3:52 am 
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renegade74 wrote:
The last freelance programmer I spoke with said they need source data - which I now understand to be unavailable (engineered in assembly only).

The reason the source code isn't available for comercial games is because the developers normally wouldn't give out such company secrets in the first place. It has nothing to do with what language the game was written in. Hacking a game means to figure out how it works without the original source code.

Quote:
d) Yet another is offered by a new coder offering to do my game in level creator...of which program, and how it'll turn into a .nes file...I don't know.

As a general rule, I wouldn't assume anything can be easilly converted to a format that works on NES hardware. There certainly are exceptions but not big things like a whole game.
Some people prototype their games in a high-level language first, then redo the game from scratch for the NES though.

Jedi QuestMaster wrote:
creating a homebrew requires much more intricate knowledge compared to hacking (reverse engineering), at least based on my experience.

IMHO creating a game from scratch is easier than hacking existing games (simpler hacks aside), though mostly because I have very little experience in hacking games I guess (I'm still a newbie coder as well).
But no matter if you go with hacking an existing game or make it from scratch, both paths would require understanding the NES hardware, 6502 programming and also some general game programming knowledge.

I'd recommend the Nerdy Nights tutorials if you want to learn to do it yourself.


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PostPosted: Sat Feb 25, 2017 7:38 am 
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renegade74 wrote:
c+) or, write an importer program that recognizes tiles from the image maps and imports them that way.

c+ is exactly how level backgrounds in Haunted: Halloween '85 and The Curse of Possum Hollow are made. But compared to most NES games, those games prioritize hiding the grid over things like storage efficiency and destructibility of backgrounds.

In any case, unless something is actually private, it's best to keep the replies in the forum so that anyone with something meaningful to contribute can contribute.

Is there a reason you want to use existing levels rather than creating your own?


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PostPosted: Sat Feb 25, 2017 12:15 pm 
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thanks all, guess I'm still not sure what skills the coder needs besides 6502 and in what program he would perform that in.

the game I'm using is on the rare side so not drawn out like a Super Mario Bros. 3 for example....how can you import and unscramble? Can you do anything besides build a flash cart? Aren't there solutions where light modding can be done?

Thanks!!


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PostPosted: Sat Feb 25, 2017 3:32 pm 
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renegade74 wrote:
how can you import and unscramble?

Import level data to your game? You would have to design your level engine so that it takes the same format of the level data. Else recreate the data so that it matches what your level engine expects.

Usually developers makes up their own format for things like level data so it is different for every game. Tools for extracting data like this are usually game-specific.


renegade74 wrote:
Can you do anything besides build a flash cart? Aren't there solutions where light modding can be done?

I don't follow. There are flashcarts available for purchase so you don't need to build one. Not sure what light modding you are talking about.


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