Science / 361875

Have you ever reverse engineered anything?

Right now I'm in the process of digging around Petz 5 files. (mostly to learn reverse engineering and I wonder how my childhood games ran)

I'll post some findings here and invite you to do the same.

Picrelated: Ruckingenur II: The Hardware Hacking Game https://www.zachtronics.com/ruckingenur-ii/

Bernd2026-06-21 17:08:49 · 4dNo. 361995 reply

Wikialleys

image/png 19.00 KB

I finished my initial analysis of the "Alley Cat.cat" file. I presumed this file would just be data about the "Alley Cat" breed, but it was a whole executable compiled in C++.

Pic related, the Alley cat in question. (https://petz.miraheze.org/wiki/Alley_Cat)

I have downloaded HxD to analyze the file (it is a hex editor).

I went through it while documenting what's happening at each offset. Mostly the plain text because I'm not good at analyzing hex yet.

Offset: data.

Header section - Beginning.

—0: Beginning of the header section. MS DOS signature. "This program cannot run in DOS mode".

—1F1-296: Strings: text, rdata, data, rsrc, reloc. These are Windows portable executable headers.

Headers - End. (at 0xFFF)

Text - Beginning. (at 0x1000)

Text - Ending. (at 0x2fff)

Rdata - Beginning. (at 0x3000)

—3000: 32 bit structures that are likely array of some game data/lookup table

—3BAB: Section of FF's. Around like 168 FF's? I am not sure what these are for.

—5434: Import/Export table? Shows C++ functions

Rdata - Ending. (at 0x5fff)

Data - Beginning. (at 0x6000)

—6150: String table begins. Contains emotional states, personality traits, item properties, various filepaths in PtzFiles.

Data - Ending. (at 0x6fff)

Rsrc - Beginning (at 0x7000)

—8740: UTF-16 little-endian filenames (Breed sounds, etc)

—0x92E0 AlleycatSprite definition. Petz 5 uses c++ classes with inheritance, and AlleycatSprite is that for this breed.

—BCF0 data structure for the rigs, ie this is where the ingame sprites for cats are programmed.

—14D60 a lot of filenames for audio again (a lot of toyNN.wav files, etc)

—31450 onwards: This section is long as FUCK because there's a bunch of wav files for some reason. Like not filenames but just straight up audio

Rsrc - Ending (at 0x138fff)

Reloc - Beginning (at 0x139000)

—Some weird binary data in the middle of nothing here. Looks like an index and it refers to the rdata range.

Reloc - Ending (at 0x13afff)

—Somewhere here there's a lot of export strings, and interestingly enough there's pretty much all functions you can think of named here. Some examples:

>GetIsBehindPetDoor

>IsThisAPet

>AreWeIncestuous

>MutualHorniness

This is the most exciting for me because I'd like to get to the logic behind these exactly.

Tdb - ffdff000 to ffddfffff

Bernd2026-06-21 17:59:12 · 4dNo. 361998 reply

https://github.com/thenickdude/PetzA Here's a mod that allows the player to do debug-level stuff in the game. I have always been fascinated by this kind of stuff. Maybe I'll recreate my own small version, just to learn.

I'll compile a small reading list on the subject also. What's interesting is how there's vastly more resources for this than for something like digital forensics. (from what I saw)

https://www.starcubelabs.com/reverse-engineering-gba/ - I'd be interested in understanding romhacking further.

https://www.starcubelabs.com/reverse-engineering-ds/ - same but for a DS game

https://www.reddit.com/r/programming/comments/y8hb6z/wrote_a_blog_post_about_work_i_did/ - Cracking the compression algorithm for a DS game. Also people seem to like OP's writing style, I should take some notes.

https://medium.com/@valeriy.krygin/reverse-engineering-a-videogame-part-1-know-your-tools-7906f9bd0e3e some article idk I want to check it later

https://github.com/kovidomi/game-reversing - general basics

https://ssno.cc/posts/reversing-tac-1-4-2025/ - CoD anticheat analysis

https://connorjaydunn.github.io/blog/posts/denuvo-analysis/ - Denuvo Analysis. There seems to be a lot on the subject

I'd also be interested in finding material for more complex and modern games, too...

Maybe I should be putting an effort to backing up all that data in a personal library or something... Could be useful.

Bernd2026-06-25 09:31:30 · 5hNo. 362112 reply

While trying to find a reverse engineering report to imitate, I stumbled upon these lovely malware analysis writeups. They have screenshots and everything so might be good for reference.

https://github.com/itaymigdal/malware-analysis-writeups

This seems decent formatting wise. https://vaktibabat.github.io/posts/Analyzing_A_Trojan_Horse/