This is the first part of The History of Sonic Adventure DX Modding article. If you haven’t read already the introduction of this article/topic, you can do so by clicking right here.

In this Part 1, we’ll discover the origins of the very first hacking efforts in SADX along with recalled experiences from several community members (which I had previously interviewed), as well as the rise of the group known for specializing in this area, X-Hax, and takea look at many of the earlier mods with both the way they worked and how impressive they were at the time, as the complete maturity of modding tools for SADX wouldn’t come until years later.

First of all, while almost all information found on the internet regarding SADX hacking/modding begins from 2009 and onwards, it is possible to shed light on both the the years before 2009 and the X-Hax community (where a lot of the hacking development progressed) with both oldbies and (relatively) recent members. Thanks to several members of the X-Hax community, most of which are known developers of amazing mods for SADX that are used nowadays, I managed to acquire more background information about this (through their interviews). All had their fair share of comments on their experiences before X-Hax, when they joined X-Hax, and what inspired them to work on their excellent support for SADX.

In the earliest days, I was just a middle schooler on Sonic CulT, a site that I definitely had no business being on. I was drawn in by the idea of a highly invested group of extreme enthusiasts curating fringe knowledge that was hidden or otherwise hard to acquire. Eventually, there was some forum cross-pollination with Simon Wai’s Sonic 2 Beta forum, which, if I recall correctly, sprang up around the stolen Sonic 2 beta release named after the aforementioned Simon Wai. It seemed like a more active place with more technical discussion, so I migrated. It was a healthier place too. That place would go on to become the Sonic Retro we know today.


I got my start on a really old website called The Glowing Bridge working with Sonic Rom hacks. That was around….2005? I wasn’t super active on there, and I didn’t do a whole lot of rom hacks either. I did eventually find myself super involved with the community in 2007 when a close friend of mine introduced me to Sonic Adventure DX texture mods. I joined a forum called and have been deep in the community ever since.


I distinctly remember writing a self-introduction on Sonic-Cult forums (and getting accepted!) when I was in junior high school, so that must’ve been sometime around 2002-2004. I wasn’t particularly active there though. I became more active when I found out about fangames and SFGHQ and decided to join, which was probably in 2003 or so. I was also a member of a Sonic forum called Sonic-World, which I think I joined in 2003 or 2004.


Of course, key members had their beginnings in different Sonic communities, all brought over their childhood experiences with Sonic games; but one in particular that would be important for the union and further discussion of SADX mods would be Sonic Retro, which interestingly enough, had a validation system where you needed to use wisely your 20 trial posts to be promoted a member, but waste them or act like a fool and you were out of luck; was a bit strict but also effective for quality control. It also had a bit of a convoluted story about how it came to be.

I joined Retro in 2010 but I think it took about 7-8 years to actually be able to post due to the validation system the forums had. I think that was for the better in the end though, I would’ve looked really stupid on there if I’d been allowed to post back then lol.

A flowchart of Sonic Retro’s history (borrowed from its own wiki)

[Sonic Retro] was certainly a more technically-inclined place at the time that I joined. There was lots of valuable info, and lots of research going on with… let’s be real, mostly the classic games. That was a little disappointing. But, I took that as a challenge. I intended to generate more interest in Sonic Adventure. I think I did fairly successfully, but there was somebody else that joined the scene later that really got the ball rolling. 😉


X-Hax itself would arise from JCorvinus and his other friends’s passion for Sonic Adventure DX and hacking it, as at first it was just a website for his mods, but the community that it spawned would keep growing and growing, spawning its own forums in 2009 (though it is no longer working and near-to-nothing got saved even on Internet Wayback Machine) and even an IRC channel in 2010.

It was originally a website to show my mods, and then when I started getting help from my friends, I made a team page and added them to it. If I recall correctly, the original team was me, Polygon Jim, Jeztac, and Hinchy. SANiK was my primary mentor, he taught me how to work with a hex editor, as well as understand pointers and data structs, and even gave me a light intro into C programming.


Uh… Oh man… [The day I joined X-Hax] was definitely after I joined Sonic Retro, so some time after 2008.


I think [I heard of X-Hax] around the time MainMemory officially joined the scene which was 2009. I know as the previously mentioned forum died out, I made the move to Sonic Retro and got a little bit closer with members of x-hax, but I wasn’t modding the game as often. I remember really old conversations with JCorvinus on AIM (man I feel old) just before this. I got to know him and PolygonJim pretty well at the time I feel like. When MainMemory made those posts on Sonic Retro back in 2009 for SADX Modding (specifically a truly playable Super Sonic), it caused a surged in the SADX community. It got me back into modding the game, and got me on the x-hax IRC and x-hax Forums. I guess that’s about the time I “joined” the crew officially.


Interestingly, some of the core members involved actually joined X-Hax quite later over the years (including myself):

It was in summer 2016. I was running out of trial posts on [Sonic] Retro, and SonicFreak94 suggested I join the IRC channel to continue the conversation about Dreamcast lighting. It was a lot of fun (and still is) talking with SonicFreak94, MainMemory, ItsEasyActually and everyone else discussing the secrets of SA1/SADX and the Dreamcast. […]


I didn’t join X-Hax until way later, in May 2018. That was when the Discord server was first put up – I didn’t like IRC so I barely ever went in there before that. The first day was pretty funny in there because on the first day of a large server it always gets quite spammy with everyone flooding in. I don’t think I talked in there too often for a while after that, because I didn’t know anything about modding with the disassemblies at the time so it all looked confusing.


I joined on day 1 of the Discord launch. I joined the IRC for a bit back when the SA Autodemo came out, but I didn’t understand back then that people dont respond right away, so I did quit afterwards lol


And in this community, further hacking would keep being developed piece by piece. Initially everything was done with a lot of hex editing and some primitive tools like a basic model searching tool and a text editor. To give context to what that involved, hex editing consists of editing files manually through a hex editor, general-purpose tools (instead of specialized SADX modding tools, as they didn’t exist yet), and the process of finding the addresses for what you want to change. From there you experiment with editing the values, often resulting in trial-and-error. A memory editor also was made available by GerbilSoft, a known tech member from Sonic Retro, in December 2004.

Way back when, I used some tools I think I still have archived on my website to this day: Nettapu’s PVM unpacker and creator, PaintShop Pro/Photoshop 7 (Both of which I had legit copies of from a family friend), a Hex editor (Hex Workshop was my preferred. HxD SUCKS!!!), and Cheat Engine (still useful for debugging ANY program to this very day)


At the time, I used Hex Workshop, Photoshop, and Nettapu’s pvm tools. After that, I started creating my own tools. I made a series of MaxScript tools to convert 3ds max models into chunks of binary data that could be injected directly into the game executable.


Back in the day, it was specifically 3DS Max and Photoshop. I remember two really old community developed tools, PVMEdit which only allowed us to use bitmap files and SetEdit for editing the object layouts. Both were a bit of a pain to use and limited, but they really got the job done at the time.

Screenshot of Hex Workshop, used heavily back then for hex-editing SADX files.

Texture editing also was also possible that year with the creation of PVM packing and unpacking tools, and the PVR exporter plugin for Photoshop (both PVR/PVM being Dreamcast graphic formats), which has an interesting origin. You see, this plugin with the filename “pvrtex.8bi”, actually comes from the SEGA Katana SDK. If you aren’t familiar with that name, “Katana” is the Dreamcast’s development name. This meant that an official tool from SEGA was used in order to accomplish this (at least until more advanced tools could replace its functionality).

Another tool that was used for texture editing later on is PVMEdit. This tool provided functionality for opening PVM files, having previews for its textures on the fly, as well as replacing textures (though the texture size/resolution wasn’t changed). Yet another early tool for SADX mods back in 2004 was SADXsnd, made by SANiK. We could consider SANiK one of the main pioneers behind SADX modding with his early involvement and mentoring of key members like JCorvinus. More detail about SADXsnd will be given later with all the other tools.

PVMEdit allowed you to replace textures but the resolution of them stayed the same. If the image was larger then it would only contain that part, if it was smaller the rest was filled up with a color. Also I remember it bringing up a popup about the texture and one afterwards about the mask.

r543, member of X-Hax Discord channel

[…] It was quite lacking in the tools department. We had really unreliable software like PVMEdit that people insisted on using which was completely busted, hex editors were required for everything else, etc etc. It was not the most welcoming, but certainly a lot of fun if you were willing to put forth the effort. I learned a lot this way.


While there isn’t a lot of info about the older sites dedicated to SADX mods, these of course still existed. One particular site that seemed to be quite popular between 2008-2009 (pre-demise) for texture mods was

[…] was a community that was mainly SADX modders. I met a lot of folks on this website, some of whom are still around under new aliases (I’m one of them, used to go by darkspinessonic35/darkpines35 in the community), most of whom have vanished from the scene. I learned a lot of my early stuff from this website with modding SADX specifically, in particular editing model’s vertices and SET (Object Layout) editing. The site itself was unfortunately home to a lot of drama which eventually led to its downfall. Little too much toxicity from the folks who ended up running the site when the admin decided to leave the scene.


As was common in the earliest years, most mods were based on modifying the textures through the aforementioned tools. Often they involved either retextured characters, or retextured levels under a “project” banner. However, these places also were what generated other users interest in SADX modding. Larger userbases would be important for support (and expectations) for bigger things to come.

I remember a Dreamcast character model port and a whole bunch of “original character” mods, which I couldn’t really get into. There was also an “SADX MIP pack” mod [from July 16, 2010], which added mipmaps to most textures in the PC version. It improved the look of the game a lot and I think it was one of the essential mods before the Mod Loader.


(These are pictures from January 27, 2009, from a post made by sthdx in Note the retextured levels, Metal Sonic, and HUD)

Speaking of mods, there were a few tutorials at While most of the website was archived, the tutorials themselves unfortunately were not. We can assume, however, that these were guides on editing the .PVM (texture) files for whatever you wanted, as well as replacing/changing WMA files (which was the format for voice clips and music in stock SADX 2004).

On a more general note, at first the closest thing to model editing that was available was editing the model vertices. But after 2008 some progress would be made on that front with JCorvinus hacks during 2008-2009.

One of the first projects JCorvinus worked on was Shadow Adventure which was intended to have stages with edited object layouts, texture edits, and Shadow playable instead of Sonic. At the time, though, there wasn’t much to work with in terms of tools. From both JCorvinus’s mention, and the similarity with Super Sonic (notice the spines), it can be assumed that Shadow’s model was being done by having Super Sonic’s head model over Sonic’s and replacing the texture with a modified one. And on top of that, as there wasn’t a proper SET layout (object layout) editor or tool, everything was done through hex editing and trial and error with testing the game.

[…] I do remember that the earliest modifications were texture modifications, then object layout modifications. I do remember that myself and many other people, having played Sonic Adventure 2, and wishing that Shadow had been in the DX port of Sonic Adventure, all converged on this idea of figuring out how to get him in game. I think I was the first to get something working by modifying the data to have Sonic’s character graph node to point to Super Sonic’s mesh data, then doing a texture edit.While working on the Shadow Adventure project, one memory I have that sticks with me, is that in order to work on the SET layouts, I needed a dictionary of what each item type did in each stage. I spent many late nights in a hex editor, incrementing an ID value, saving the file, loading up the level, writing down what the object was, and repeating it until I had a full list. This was before we knew how to scrape the executable for the item names, or that they were even present.


However, outside of a demo that may or may not be lost to time, the project was accidentally wiped out:

So I was having issues with sonic.exe and I assumed it was a problem with Windows. After trying for a while to fix the issue, I finally decided upon a drive format. Shadv was on a different partition than my Windows install, so I used fdisk to clean the drive – well it turns out fdisk ignores ntfs partitions, so I managed to single-handedly destroy shadow adventure, completely with the sole exception of the demo version.

JCorvinus, Shadow Adventure page in Sonic Retro, 2009

After that, he started working on two things: a model swap mod that used Sonic’s original Dreamcast model (albeit without the morph head model used for talking in cutscenes), and Sonic RDX, which was an ambitious project that attempted making new levels by rearranging original level objects and geometry. Regarding the DC model for Sonic, it mostly involved copying the data of the original model into the DX version, minus the hands and shoes. This was done with the intent of being better than the original and avoiding complications which could break something. The morph head was also bypassed through a trick, allowing the Dreamcast Sonic head to stay on at all times.

It was a straight data port, I just copied mesh and material data over and ported textures and modified texture IDs to match. I forget exactly which trick I used at the time but I did find out that you could break the speech morphers by messing with how the pointers were structured. So I used that to keep the dreamcast head around at all times. […] Also, keeping the original arms, shoes, and hands prevented the runtime vertex system from breaking.


However, the very first, fully custom model, that wasn’t a model or data rearrangement, would happen in 2010. This was model was part of Sonic RDX, replacing the Super Sonic gold question mark model with a Sonic icon through a work-in-progress exporter. MainMemory would also develop several useful tools for SADX hacking, including SETEdit and SADXLVL

The island that shows up at this time stamp [1:26], at the end of the pier, is the first piece of level geometry that was ever moved successfully, because I had finally figured out how to re-calculate the bounding spheres.

JCorvinus, referencing the Sonic RDX Demo video

Sonic RDX itself was especially ambitious for what was possible at the time. It replaced the music tracks, textures, and of course, new levels through rearranged layouts. The last demo even had four modified levels based off Emerald Coast, Speed Highway, Ice Cap and Red Mountain. While it may not have aged well due to how early it was (it looked like a mishmash of level objects, having some issues like invisible springs, and the camera being unmodified causing weird things to happen), it definitely was groundbreaking both for the modding community and the potential that was yet untapped in the SADX modding scene.

I remember playing Sonic RDX, and its weird imagining that it was made through a lot of hex editing, instead of just a couple lines of code in a .dll file like its done nowadays.


[Sonic RDX] was a huge project. Ever since learning about modding, there had always been these off-handed mentions about ‘total conversion’ and how they were the biggest, most ambitious mod projects out there. Modifying a game so much that it essentially becomes a new game.


With all that in mind, it is clear that there were a lot of aspiring young users creating texture/model mods, as well as others trying to do something even bigger than usual.

Rough around the edges is the best way I’d describe it [The early SADX modding scene]. It was well before the days of the ModLoader, so all of our game modifications were limited to editing vertices, textures, and the object layouts. Some cool stuff was definitely done back in those days though. Plenty of awesome object layout edits and lots of cool re-textures to the game. I do know that a lot of us in that early scene looked up to JCorvinus (known as Dude) at the time and a few others. He was the first person to make a complete overhaul to a level, something that all of us wanted to do at the time.


At this point, we have mentioned that texture replacement was a thing, and so was creating modified models through editing vertices. Now, with the idea of custom Sonic characters always being around in the community, it would spawn many character mods, that either were simple texture replacements, or were both an texture replacement and modified model, which around this time, ALWAYS needed an custom CHRMODELS.DLL file.

The mod loader wasn’t around so you had to keep a back up of all the original files and overwrite them in the system folder directly. The biggest mod at the time was Sonic RDX, because it was the only one that changed the stages. Everyone wanted to make a mod like that, but nobody really had the skill – what was more common at the time were model edits of Sonic running around retextures of Emerald Coast, probably with different music. That stuff was all simple enough to comprehend.


These character mods, often replacing Sonic, would come with a modified CHRMODELS.DLL file, an accompanying .PVM texture file (and in most cases, a SON_EFF.PVM for replacing Sonic’s trail color), and were quite popular for a time. With the assistance of Darkspines147, another fellow SADX enthusiast, it was possible to uncover several websites/users that had made (or uploaded) several character mods (some working, some dead but working through Wayback Machine). These included sm64no1LOL and Team-Speed (SADXHACKS). One notable creator was Zarosguth, whom had a Youtube account since 2009 and uploaded many SADX character mods, with this first one being released in May 20, 2009. Zarosguth even created a tutorial video for making your own edited Sonic trail effect.

I clearly remember Zarosguth’s mod being pretty popular with character model modifications. I have used it for quite a while myself, but after a while I always swapped to other mods. I bet many mods from the past are lost in time by now, but I will always have fond memories of them. But I definitely remember watching every single one of Zarosguth’s videos about SADX mods!


While it is true that this spawned Sonic recolors more than anything (at least until model replacements were possible), it is important to note how these worked. There would be a before and an after period where the creation of a certain tool really helped SADX modding become simpler. CHRMODELS.DLL contained data for Character models and animations, and these character hacks were made either through hex-editing this file or through SADXMDL (after it became avaliable). As well, SADX contains other kinds of model files in .DLLs, such as landtables (the term used for stage models in SADX).

Screenshot of SADXMDL, with Sonic’s stock model (posed in his standing animation) and texture loaded from CHRMODELS.DLL and SONIC.PVM.

One particular user, Fiamonder, was quite creative with whatever tools were avaliable back in 2010 and SADX mods. The first one we can mention is about how he made a Kirby mod for SADX that actually looked like using custom models (because, well, Kirby was properly round and short arms; some things like animations were weird but it worked). He would later port some few Sonic models from other games in 2011.

Now, the aforementioned Fiamonder didn’t just do a Kirby port. He was also working on some custom levels which can be assumed to be a mix of imported models and RDX-style rearranged set pieces (this is judging from one of his only surviving levels with footage). In fact, his first levels were made before said Kirby port. The first video in his youtube channel is dated December 31, 2009, in which he showcased both his first object layout edits and an edited version of Emerald Coast. The later featuried a heavy amount of object layout and texture changes (though, while it may look like it, there were NO level geometry pieces moved).

That first edited Emerald Coast level would be released in February 2010 as “South Island”, featuring a few changes from the original video (such as some altered objects and slightly different textures). Interestingly, as it is composed by three replaced texture files and a altered object layout, it can actually be played in current SADX by creating a mod folder. Note, though, that back in 2010 you had to replace the files in the game folder as the mod loader didn’t exist.

A few weeks later, he would showcase Cyber Central which was inspired by a similarly named zone in the fan-game Sonic Advance 3. This zone was looking like a much more ambitious Speed Highway edit compared to the very early rendition which was little more than texture replacement and small object replacement. However, unlike the previous stage (which miraculously still has a working download link), this one wasn’t released for a while. An altered incarnation got released in 2011 which was different from the original but still had a fair share of changes. Unfortunately the download links for either version no longer work.

Fiamonder would keep trying out ideas for custom SADX levels in 2011, including a test level where he used a JCorvinus’s beta tool for importing models, importing Bob-Omb Battlefield (which was in Feb. 2011; before JCorvinus’s Mushroom Hill, but this one wasn’t released and had some few polish/camera issues), and also was working on the “Sonic Bluefire” project from which hehad previewed Act 1, Act 2, and Boss of Angel Island, and Frozen Paradise. While there was a demo released in 2012, there were no surviving download links.

He would also work on some interesting custom levels inspired by other Sonic game stages, among other things. These included White Jungle (SA2; this even had a Shadow model import), Seaside Hill (Heroes) and Crisis City (STH06). However, Crisis City would be his last mod before moving on to do some unfinished Generations mods and then disappearing from Youtube.

Zarosguth himself would also attempt custom levels at one point, starting with Chaotic Caverns. While this one had a lot of rough edges, such as floating models and overall lack of completion, it was still pretty interesting considering the time it was showcased (May 2011), the replaced jumping animation (doing a spinning kick instead of curling in a ball) and the 2D section.

The release of SADXLVL (a level editor tool; more on that later) back in 2009 made modifying levels something accessible to a wider range of users. This was thanks to rudimentary model import features and a visual interface which allowed the previously mentioned Fiamonder and Zarosguth to create custom levels. However, it would notably be used by JCorvinus to make a whole new, properly finished and fleshed out custom level: a Mushroom Hill themed level released in July 2011, made with the use of his new model exporting tool. It even featured a whole new camera set designed for the level. This would be one of the most advanced mods for SADX released in 2011.

Mushroom Zone represents a maturation of the tooling. It was the first time I was able to design (and finish creating) a level pretty much from scratch, with barely any technical consideration of the existing stage. It was the first stage I completed entirely using SALVL as the primary export tool. The ability to treat it as its own stage instead of a modification of an existing stage meant that I could start from level design as a discipline instead of just making whatever came to mind and focusing just as much on the technical craft of getting the data in-game as what the design of the level should be. It was very liberating.


Like all other mods before the future Mod Loader though, it would require you to replace the original files. But since it featured a completely new stage model (on top of custom cameras and object layouts), it would use a new .EXE file as well (since the landtable data is stored there). It replaced Windy Valley and it used several of its objects. However, it would need to stay within some limitations related to that stage. Because of this, some ideas that JCorvinus intended for the stage weren’t possible yet.

There were still some limitations though. The original version had to fit inside of the original game executable, and had to have fewer scene graph objects than Windy Valley part 1. I was also unable to make classic loops that the player runs though, as there some of the spline data structure was (and remains to this day) not understood.


Another interesting project from 2011 was SonicFreak94’s Sonic Adventure DX Fixed Edition, first released in May 28, 2011. This mod brought texture filtering fixes, tweaked item layouts, mipmapping, stage geometry fixes, and restored some small visual details that were present but unused due to a glitch. Overall, it helped iron out some of the port’s strange changes and made the game feel more consistent.

The tool that would make one of the biggest differences in future modding would be MainMemory’s SADX Mod Loader, released in August 3, 2013. Not only would it allow for more organized mod installation but also data redirection, which would open more possibilities for creating custom content. On that note, many of the tools that MainMemory made would also have partial functionality with the Dreamcast version and these would be crucial in figuring out many mysteries of the game. These discoveries would later lead to bigger things being possible after many years of research…

Its weird to imagine an SA1 or SA2 that has no tools, no SAMDL, no SALVL or anything like that. Without all the efforts through all these years, I wouldn’t be here making mods and stuff.


Thanks for reading the History of Sonic Adventure DX Modding (Part 1)! The original concept was to have all the sections in a single article; but as a way to allow some gradual ease in reading the whole thing, these sections that cover the entire topic will be spread out in separate posts. You can find the next one and all the others in the index below.

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If you liked my content, sharing this with others helps me out; and you can lend me a hand through my Ko-fi page as well! I had delayed a bit with putting out this first part but I’ll be working to put out the rest in a faster rate. But until then, I hope you have enjoyed this!