This is a list of all distinct Sonic Adventure (+DX) versions that can be obtained today as far as I know. Originally I wanted to make a branching timeline of SA1 builds, but I couldn’t find a good way to put it on a blog, and I also realized some builds, like the Autodemo, don’t necessarily fit in a single timeline, so here’s a list instead. There is also a lot of information on SA1 development on TCRF, which I recommend if you want a timeline of SA1 development with screenshots and other details.

Dreamcast builds

Let’s start with the original game on the Dreamcast. Note that I’m not including builds that we don’t have, such as the Tokyo Game Show demo and the version used for the Tokyo International Forum unveiling video (assuming the footage comes from a single version of the game).

Gamecube builds

On the Gamecube we have two very interesting prototypes which fueled a lot of SA1/SADX research. Much of the knowledge on the game’s internal workings came from the first Preview prototype years before we got the X360 version with debug symbols. Apart from the prototypes, the builds on this platform haven’t been studied as thoroughly as the Dreamcast version. It is notable that the Gamecube ports have sequenced sound effects, which use a Gamecube adaptation of the MLT file format that was originally introduced in Dreamcast SDKs. Interestingly some character grunts are similar to the ones found in the E3 1999 version of SA1 DC, and some changes to assets are similar to the Autodemo and early prototype screenshots of SA1, but that’s a topic for another post. There is no doubt that SADX code is based on a later version of SA1, most likely 1.005 or International. Also, all versions of SADX have a leftover texture archive with title screen textures from SA International.

PC builds of Sonic Adventure DX (2004)

There are two distinct “base” versions of SADX PC – the original 2004 port and the “Dreamcast Collection” 2010 port. The 2004 port is where it gets really complicated as there were releases in different countries and the details on the actual differences are fuzzy. There are versions released in the UK, Germany, France, Spain, Italy, Hungary, Sweden, Australia, Israel, Brazil and Singapore, which may have minor differences. I know for sure the EXE in the Hungarian version is different from the “regular” European version. However, I must also say that the differences between these versions are so minor that almost all assets in sonic.exe are placed at the exact same addresses as the US version. One notable exception is the Korean version, which I have included as a separate entry in the table.

All versions of the 2004 port share the same features and downgrades. The 2004 PC port is based on the Gamecube port as it contains strings mentioning REL files. One interesting thing about the 2004 and later ports is that they use the blue water texture in Emerald Coast, which was used in prototypes but replaced with a green one in the final version on the Gamecube. The 2004 version uses WMA files for music and voices unlike the versions before and after it that use ADX. This port also abandons sequenced sound effects and switches to a different soundbank format containing raw PCM WAV files.

The new ports (2010 onwards)

In 2010 SEGA released a bundle for PS3 and X360 called “Dreamcast Collection”, which contains ports of several Dreamcast games including SA1/SADX. Although it is bundled as “Sonic Adventure”, the core game in these ports is based on the 2004 PC version of SADX. However, it does put back the original Dreamcast title screen with ripples. While they share almost all of the downgrades of the original 2004 PC version, for obvious reasons these ports have completely different rendering and sound systems that were developed by SEGA of China. They use shaders for character lighting and switch back to the ADX format for music and voices. Interestingly shaders and textures for water distortion are also included, which suggests that they were going to reintroduce Gamecube water effects, but there is no water distortion ingame. In addition, the soundbank format was revised, and sound effects switched from WAV to ADX.

These ports also introduce many additions wrapped around the original game’s systems, such as a texture replacement hook using DDS textures, support for achievements and online leaderboards, a different main menu system, new screens for credits, controls and tutorials, new fonts etc. Game Gear games are inaccessible (but still technically there), while Mission Mode and Metal Sonic are unlocked via a paid DLC.

This collection was also released on PC twice – in 2011 (physical) and 2016 (Steam). The 2016 version is known as “Dreamcast Collection Remastered”. Little is known about the differences between the 2011 and the 2016 versions, but on the surface they appear to be the same. The version of SADX currently available on Steam is the Remastered version. The Steam version comes with the DLC force enabled, and the Dreamcast title screen is inaccessible. If enabled via hacking, the DC title screen is a static image, although the model for the animated title screen is present in the binary.

These ports are the least researched and for the most part don’t present much interest. However…

X360 prototype builds

In 2020 several development builds of the X360 port were discovered, including a near-final build with debug symbols. The debug symbols have helped a lot in identifying assets and code in the PC version. I’m listing all known builds of the X360 version, including the final one.

If you own a rare version of the 2004 port, let me know! The Korean version was a big surprise and very interesting to look at. Maybe there are more unique versions out there?

This is a CodeBreaker code for SA1 US 1.005 that disables all cutscenes. It works exactly the same way as the “Skip All Cutscenes” code in SADX Mod Manager.

010496B4 0900

Cutscenes are removed by nopping the function call that starts the cutscene code, which makes the game assume the cutscene has finished playing. The address of the call is 0x8C0496B4.

There are a couple of small glitches when this code is used. For example at the start of Sonic’s story you can see Sonic in Station Square before the screen fades out and the fight with Chaos starts. This is how it’s actually programmed – the game loads Sonic into Station Square before initializing the cutscene. You can see it briefly when you start Sonic’s story without the code. A similar glitch happens in Station Square in Knuckles’ story.

There are some other potential applications for this code. For example, a conditional code could be made to activate cutscene skip when a certain button combination is pressed, and restore original behavior when it isn’t pressed. That way you could skip individual cutscenes by holding a button when the cutscene is about to play. It could also be made into a simple toggle. Of course it’s not as straightforward as simply pressing a button during the cutscene to skip it, but it’s still pretty good.

The first Sonic Adventure on the Dreamcast had a Black Market just like the sequel. The archived version of the original website still has the pages and CGI scripts for it, as well as VMU files, which we’re going to look at today.

I didn’t access the Black Market back when it was online, but I’ve heard that the US version never worked because of some bug. The messages from Chao Doctor all the way to January 2000 mention that the Black Market was about to launch, and the comments in the CGI script used on the website suggest it was indeed broken at the time of archival:

The Japanese version was functional though, and it was possible to download several jewel Chao. The Ruby and Emerald Chao didn’t have any emblem requirement. It looks like they were given out “for free” to celebrate the Dreamcast’s US and EU launch anniversaries. However, according to this page, the Emerald Chao was released during an event “Magical Garden: Yume no (‘Dream’) Dreamcast Festival” that took place on March 27, 1999. I can’t find any other information on the event so I’ll have to leave it there for now.

The Amethyst Chao was unlocked when you had 100 emblems. The Sapphire Chao isn’t referenced in the pages or scripts but its VMU data exists. Apparently the US version was going to add a new “NiGHTS” Chao that would also cost 100 emblems. Although the NiGHTS Chao is referred to as “very special Chao”, it’s actually a regular Fly type Chao with animal parts rather than a unique character Chao, which SA1 doesn’t support anyway.

Chao downloads are stored in 8-block VMS files, and Japanese files have a different header although the data is compatible between all versions. There’s a script on the website (likely used for Chao daycare) to generate Chao VMS files, and it alternates between Japanese and US headers, which are stored as binary data on the website. The header is set up like a VMU game header, similar to Chao Adventure. Here are all the files found in the site’s archive:

Description	VMI file	Screenshot	Emblem requirement
Emerald Chao	CHAO_EME		0
Ruby Chao	CHAO_RUB		0
Amethyst Chao	CHAO_AME		100
Sapphire Chao	CHAO_SUF		?
NiGHTS Chao (US only?)	KNIGHTS		100

I’ve also made Chao Download data for BUDDY, the developer Chao mentioned in my previous post. Download it here to get it in your copy of SA1 DC.

There are a lot of mysteries about Sonic Adventure’s files on the VMU, some of which we’re going to unravel today. I’d like to also use this post to list known VMU filenames in SA1 for future research.

Let’s start with the better known stuff. The main save file is called SONICADV_SYS in the original Japanese release, and SONICADV_INT in all other versions. The newer versions contain text and voice language settings which aren’t available in the original Japanese version. Normally the Japanese version doesn’t load US/EU/International save files, and vice versa. However, the game will recognize the other version’s save file if you rename it.

Now let’s talk about Chao files. The main Chao save is called SONICADV_ALF and is compatible between all regions. When you take a Chao out for a walk using the VMU-shaped transfer machine, the game creates a file called SONICADV__VM on the VMU. This file contains the VMU game Chao Adventure with the Chao’s data written directly into the game file.

The filename SONICADV__VM was also used for Chao downloads from the website. In the Japanese version of the game you could download rare Chao (Sapphire, Ruby, Emerald) from the website if your main save file had a certain number of emblems. These are discussed in a separate post.

Upload Data

There’s also a bunch of files that are created on the VMU at certain points in the game. These files were meant to be uploaded to the official website using the game’s built-in web browser. Among such files were Chao, level clear times and results of DLC challenges. They contain an HTML page with a hidden field that contains encrypted data encoded as a Base64 string. The encryption is the same between these files and DLCs.

The Japanese version had different strings for the webpage so the embedded HTML is different from later revisions, also the Japanese version uses different filenames. Here are all of them:

Hidden Chao on SA1 US GD-ROM

Interestingly there are files SONICADV_H00.BIN and SONICADV_H04.BIN in the root folder of SA1 US GD-ROM. These appear to be earlier versions of the data produced normally by newer revisions of the game. Apart from using the Japanese version’s naming scheme they have some differences in HTML compared to the regular files. While it isn’t compatible with either version of the game, the interesting part is the actual data stored in these files.

The Chao file contains a baby Chao called ♥BUDDY♥ that was submitted by segaeigh@concentric.net. Yep, there’s been a Chao hidden on the game’s disc all these years. Here’s what it looks like:

Eventually you’ll be able to edit Chao upload and download data, including this file, as well as the main Chao save. I just need to get to writing a Chao editor for SA Tools.

Character Voice Packs

When one of these files is placed on the VMU, the game changes the character voicing the menu screens. The files themselves don’t have any meaningful data other than an icon, a description and a single string Team Andromeda. The game seems to set the voice mode based on the filename. Again, the Japanese version looks for different filenames, so there were actually 18 unique files for voice packs! Do we even have their Japanese versions archived?

Events and Challenges

A lot has been written about SA1 DLCs, and they are now fairly well understood, up to the point that you can make your own DLCs that will work on an actual Dreamcast without hacking the base game. So here I’m going to talk about things that are a but more obscure.

One major limitation of the DLC system in SA1 is that you can only have one custom model. While I haven’t been able to get the game to load more models, I got it to load a model that isn’t stored in the DLC file by editing the pointer in the DLC file’s model binary to make it point to a different location in memory. It’s still just one model per DLC and you have to supply its textures separately but at least you can load stuff outside of the DLC file if you really want to. Maybe it’s possible to add more pointers and make the game load them somehow? I’ll look into that sometime soon.

The filenames for the DLCs are SONICADV_aaa, where aaa is a number from 000 to 999. IDs from 000 to 200 are reserved for DLCs that only have text in Japanese. Early events released in Japan (Famitsu challenge, QUO challenge etc.) only contain Japanese message strings, and their string table is smaller compared to later events that had text in other languages. However, these old events still work with newer versions of SA1 with Japanese text displayed correctly regardless of the game’s language setting. The game doesn’t load strings for other languages if the DLC ID is lower than 200. This is why there is a gap between Japanese and international event filenames: the last Japan-exclusive event was called SONICADV_003 and the first international event was called SONICADV_501 (though SONICADV_200 would’ve worked too).

The Weird Stuff

The game’s main binary has several filename strings that suggests some interesting functionality. Earlier this year we learned from Exant’s fascinating discovery that we can still activate the game’s built-in lighting editor that looks like this:

Apparently this editor can load lighting files from the VMU, and that functionality seems to be still in the game, we just need to learn how to activate it. The palette file is supposed to be called SONICADV_P00, and the SL file is SONICADV_S00 (in the Autodemo they’re just PL_ and SL_). It’s possible that numbers other than 00 were also used. There is a function loading these files at 0x8C011D46 (US 1.005). It also seems like LANTERN_PALETTE and LANTERN_SOURCE were VMS titles, while ＬＡＮＴＥＲＮ／パレット情報 and ＬＡＮＴＥＲＮ／環境情報 were VMS file descriptions. I’ll experiment with custom VMS files to see if the game picks them up.

There are also some strings suggesting there was VMU to PC transfer at some point. The filenames used in that transfer were SONICADV.VMS and SONICADV.DL0. Doesn’t look like it’s used, but who knows, maybe we’ll recover it eventually.