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+title = 'Reverse Engineering _Neon Genesis Evangelion: Girlfriend of Steel_'
+date = 2026-04-22T20:30:53-05:00
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+
+Last year, I started reverse enginering _Neon Genesis Evangelion: Girlfriend of Steel_ with the intention of writing a replacement engine that runs on modern computers.
+I ended up losing interest, but not before cracking a few of the game data formats. I'm going to document them here, that way anyone who takes a similar
+interest in restoration or modding can have a head start.
+
+The source code of the abandoned project is available here: [fantatech-1776908508.tar.gz](/files/girlfriend-of-steel-re/fantatech-1776908508.tar.gz).
+It includes [ImHex](https://imhex.werwolv.net/) patterns and rudimentary decoders for some of the formats described below.
+
+## What game am I talking about?
+
+I actually looked at two different games. I will share the information I know about the 1997 formats, but the primary focus will be on the 2006 version.
+VNDB has a good record of all the available ports and translations here: [https://vndb.org/v556](https://vndb.org/v556).
+
+**_Neon Genesis Evangelion: Girlfriend of Steel (1997, PC)_**: This is the original release of the game. It's also the most widely available.
+I was able to buy a factory sealed copy on eBay. Surprisingly, you can still mount the ISO and run the ~30 year old binaries on Windows 11. It plays mostly
+fine with a [Shift-JIS locale emulator](https://github.com/xupefei/Locale-Emulator).
+The chunky bitmap graphics and audio, although charming, are considerably lower quality than in the 2006 version.
+
+**_Neon Genesis Evangelion: Girlfriend of Steel (Special Edition) (2006, PC)_**: Also called _Shin Seiki Evangelion: Koutetsu no Girlfriend Tokubetsu-hen_, is a remake.
+It has upgraded sounds and visuals, additional scenarios, and a full-motion video (Cinepak) intro sequence. It's also filled to the brim with DRM that makes it completely
+broken on any system that isn't running Windows XP with Direct3D acceleration.
+This will only run in VMWare because VirtualBox dropped 3D acceleration support for Windows XP guests.
+
+I have not been able to find a physical copy of the PC version of Special Edition for sale anywhere.
+The PSP version is available, but the image resolutions are smaller than those found in the PC version.
+
+Luckily, someone in 2020 found a copy and had the foresight to rip the disc and upload it to the The Internet Archive. This is the raw, original disc; DRM and all:
+[https://archive.org/details/ssekngpcredump](https://archive.org/details/ssekngpcredump) - [http://redump.org/disc/74520/](http://redump.org/disc/74520/).
+
+MD5: `536adbefc80a84378b65224fddf122e7` SHA-1: `77a03fb1823cb96189ac50b9afece8930e709c93`
+
+## Defeating the DRM
+
+TODO remember how I did this, then write about it
+
+## Custom file types (1997)
+
+* **BP2**: Image (1997)
+* **BP3**: Image (2006)
+* **LB5**: Lump file
+* **TXT**: Game script
+* **ZDF**: Animation data
+
+## Prior work
+
+When reverse engineering the 1997 game executable, I found several strings referencing something called "bmpwaku".
+This was the name given to the tiled bitmap rasterizer written by programmer Ritsurō Hashimoto.
+
+A small portion of the source code is still available on his website to this day: [bmpwaku.cpp](http://www.ritsuro.com/prog1/bmpwaku.html).
+This wasn't particularly useful, but it was cool to find.
+
+Aside from that, here are the existing tools I looked at:
+* [evac010](https://www.vector.co.jp/soft/win95/art/se055672.html): BP2 <-> BMP transcoder, likely written when the game came out in the 1990s.
+* [mdukat/EvaGOS\_engine](https://github.com/mdukat/EvaGOS_engine): Includes partial documentation of the game scripting language from the 1997 game.
+* [lb5\_decode.c](https://d3suu.neocities.org/EvaGOS_engine/lb5_decode.txt): LB5 unpacker, written by either mdukat or roxfan.
+* [Durik256/GOS2-Tools](https://github.com/Durik256/GOS2-Tools): Tools for dealing with files found in Girlfriend of Steel 2. Some overlap.