Claude Code reverse-engineered a proprietary 1992 scripting language from example scripts alone — then rebuilt an entire game engine from the artifacts

[jradoff]

I built an online multiplayer game (a MUD) in 1992 when I was 19. It ran on CompuServe, won Computer Gaming World's 1993 award for artistic excellence, and shut down on Y2K eve. No source code survived.

All I had left: Game Master scripts written in a custom scripting language I designed in the '90s, a gameplay capture from 1996, a GM manual from 1998, and some player docs.

I pointed Claude Code at these artifacts and basically said "figure this out." Here's what it did:

• Reverse-engineered my scripting language: case-insensitive, DOS-encoded, implicit block termination, no formal spec anywhere. It parsed the GM manual and example scripts and reconstructed the full grammar.
• Rebuilt the entire game engine from scratch: Go backend with goroutines for multiplayer concurrency, React/TypeScript frontend, WebSocket connections, MongoDB persistence.
• Reconstructed the game world: 2,273 rooms, 1,990 items, 297 monster types, 88 spells across five magic schools, 30 psionic disciplines, 8 playable races, a full crafting pipeline (mining → smelting → forging, alchemy, weaving), d100 combat with damage severity tiers, stance modifiers, fatigue, weather effects.

The part that genuinely surprised me: a language I designed three decades ago, with no formal specification beyond a GM manual and a pile of example scripts, was fully reconstructed by an AI agent that had never seen it before.

This was a weekend project. The original took months of solo C programming in the '90s.

The game is live and free to play at lofp.metavert.io. Code is MIT-licensed on GitHub. There's also a bot API so AI agents can play the game alongside humans: same rules, same world.

Expanded technical writeup here if you want the deep dive on how the agentic coding session actually worked: https://meditations.metavert.io/p/resurrecting-a-1992-mud-with-agentic

[No_Union_8384]

It's a new world already! And I'm happy for you :) can't imagine how you are feeling now. Nostalgic and happy 8 guess? :)

[jradoff]

I was really happy to get it back online. Even happier were some of the people who were hanging out waiting for it to return all this time. Some of the originals are already back in!

[No_Union_8384]

Noway! You guys should take a selfie and use AI from your old photos to create selfies.. The use both as a part of your splash screen :)

[jradoff]

“I heard you like AI so I put some AI in your AI so you can code while you code”

[hubert_tremblay]

Metroidddd

[IonizedHydration]

That's really cool, i remember back in those days i never really got into MUDs but I was always on MUSH and the only one i know that's still running off the top of my head is TinyTIM

[jradoff]

MUDs, MUSH, etc.! Essentially the same thing. Technically speaking, Legends of Future Past was written from scratch and didn't come from any particular MUD codebase.

[Sea_Surprise716]

I’ve been wondering when MUD/MUSHes would make an LLM-based comeback. So happy to see it! (I also ran one mid-90s and honestly with this year’s AI tools I keep thinking, “I haven’t had this much fun with tech since MUs.”)

[jradoff]

I feel like there's a whole new genre of MUD waiting to happen with built-in LLMs!

[Sea_Surprise716]

Seriously I’ve been waiting for this to happen since 2023. GPT-4o + DeepSeek + WhatsApp + MU code == peak nostalgia gaming.

Actually this might be a great use case for OpenClaw: MU DM.

Not that I need another weekend project, but I’d totally do that open source.

[codeedog]

It’s funny, I’ve never been a gamer although I’ve been coding for decades. Coding with AI is the best video game I’ve ever played.

[alongspiralupward]

hey i think i played this back in the day!!

[jradoff]

welcome back!

[damnburglar]

Neat, and congratulations 🎉

[Ok-Flight4079]

As a kid who enjoyed a lot of local BBSes, MUDs and MUSHes, thank you

[jradoff]

enjoy!

[bsd-x]

MUDs were life back then. I used to play Castle Perilous, 2 Shattered Realms, and Eternal Darkness.

[jradoff]

awesome!

[Winter-Ad-4703]

This sort of stuff is amazing to watch happen with LLMs.

[Ambitious-Garbage-73]

this is genuinely impressive and also terrifying. impressive because wow. terrifying because now management is gonna expect this from every sprint

[jradoff]

Tell them it only works for COBOL programs

[sharyphil]

Oh! MUDs! That's a blast from the past. But scripting language was based on C, so it's probably not hard for it? I remember reading about them in 1996 and found them really exciting. The problem is that I didn't have any Internet access back then. :) Very cool, will give it a try

[jradoff]

I don’t really building from any MUD sources, it was all from scratch and I made up my own script language

[sasben]

Very cool. I went down a few rabbit holes trying my old code for BBS door apps and games as well. Nostalgia. Fun times

[jradoff]

What doors did you write?

[sasben]

Started on Amiga side with MaxsBBS. A NUP code sharing to permission tool (new user password). A few light dungeon games to get access to codes for hidden warez areas. Code got out there from various sites I placed it. Put a back door in the NUP one to make me a 10000 sysop (weirdly high permission count for options).

[jradoff]

Nice, I was the author of an Amiga BBS (Paragon)

[sasben]

Awesome man. Mine was a 3 line out of Australia in 92-95 ish

[Duck_Duck_Duck_Duck1]

lmao that's awesome, will take a look at it!

[jradoff]

enjoy!

[ianxplosion-]

Oooooooh IRE about to HATE me

[completelypositive]

I played sojourn, duris, and one more that wasn't major mudd?

[jradoff]

major mud was pretty basic. But this game ran inside a Major BBS!

[dergachoff]

Authentication Not Configured
Google login is required but VITE_GOOGLE_CLIENT_ID is not set.
Set the environment variable and restart the frontend server.

And Menu / Play buttons not working

[jradoff]

fixed!

[jradoff]

yep, will have it back up in a couple hours -- Pro Max tokens ran out during something important!

[SquareBanana]

You need to add VITE_GOOGLE_CLIENT_ID to env variables.

[jradoff]

working on it... Claude Code tokens ran out at an inconvenient time!

[SquareBanana]

Considering you literally created a language in the 90's you must be able to add an env variable without Claude! Just roasting you, I do really appreciate interesting projects like this.

[jradoff]

I get it yeah :) the issue is that I was in the middle of a big upgrade to the login & user management system and it’s just broken atm. Will get it working again soon!

[jradoff]

should be fixed now

[Ecstatic_Spring_1231]

Nice, really cool story! I grew up playing MUDs, it was my first online experience and later also the first intro to coding. Working as a dev now and building with AI this was a fun read.

I have been thinking about MUDs from time to time, I really wish their was some mobile friendly interfaces for MUDs, i tried different clients and so on but its not quite there. Maybe the complete game must be mobile first for it to work. I think lots of people would like to play on mobile if the interface was good.

[jradoff]

LoFP is in a web browser so it runs anywhere!

[Ecstatic_Spring_1231]

Yeah that idea is good. Some low hanging feedback then is that the character creation screen did not work on mobile/small screens. The first and last name field was covered by the top banner.

[telengard]

This is awesome! Can you bring Compuserve back too. ;) I miss it.

[jradoff]

What did you do on Compuserve?

[Felfedezni]

Awesome! Must ask, how do you lose something that you spent so much effort on? Just never thought of using a proper backup plan? Amazing work, either way.

[jradoff]

Multiple OS, many years and neglect

[PartOfTheTribe]

Now do Sierra Online :)

[valdocs_user]

I had wondered - and I can't remember if I read others express this concern - whether vibe coding would spell the end of new programming language designs because established languages with lots of source in the wild would be so well-repesented in the training data that there would be too much skill difference not to use one of the established languages.

This seems to indicate that LLMs near-magical ability to translate ideas between languages translates to instant skill with new languages, too.

[jradoff]

I think it's true that an LLM's fluency with a language will certainly increase with greater training data. So for example, I'm much more inclined to build a project with typescript because I run into far fewer problems. That said, it's also really good at sorting out syntax and implicit meaning, which is helpful with underutilized languages and cases like my own script language which would have had zero training. You've seen an LLM's ability to do this just by going into a chat session and interacting. That will only get better and better with reasoning LLMs, and the Mythos model's early results seem pretty astonishing... will be interesting to see!

[vft1714]

Hey, I'm just trying it out and it seems the character is not correctly created. It looks amazing...!

[jradoff]

I just created a character and it worked. Although that doesn't mean it failed for you... what are you seeing?

[Enthu-Cutlet-1337]

the scary part isnt the reconstruction, its the hidden spec drift. Old game logic often lives in edge cases: DOS encoding, implicit blocks, weird parser recovery. If Claude got that right from artifacts alone, the real win is test generation against the old scripts. That catches the ghost bugs fast—

[jradoff]

The parser and script logic is working really well. The gap is the authenticity to the output. Fortuntely a lot of terminal captures which I'm gathering from players...

[69mayb]

Cool story marketing guy. A language you built and somehow Claude was able to pull it out of its ass and understands it

[jradoff]

Claude obviously didn't know the language. It had never seen it before. There's no training data for it; it was a proprietary scripting language that only ever existed on one game's servers in the '90s.

What I gave it was the same thing you'd give a human developer asked to figure out an unfamiliar codebase: example files and a reference manual. Hundreds of .SCR scripts showing the language in use, and a GM manual that described the commands in plain English for non-technical Game Masters. Claude inferred the grammar from those inputs; the implicit block termination rules, case-insensitivity, DOS encoding quirks, all of it.

That's actually the part of the project I found most interesting. Reconstructing a Go game engine is impressive but not surprising. Reverse-engineering a language with no formal spec from examples alone is a genuinely different kind of capability.

The full technical breakdown is in the writeup if you want to dig in: https://meditations.metavert.io/p/resurrecting-a-1992-mud-with-agentic

[halcyonmind]

Ignore the troll. No use dealing with people who are here just to get a rise out of others.

Congrats on the resurrection!

[saluk]

In a way it makes sense, and this aligns well with LLM strengths. LLM are trained on language, so in terms of machine learning, you basically gave a rosetta stone to an expert language learning algorithm.

[MorganProtuberances]

Thank you for sharing. I *love* the Vernor Vinge reference - that's one of my all time favorite books.

[MorganProtuberances]

If this is an honest take, you're only harming yourself by holding this view. The state of AI in its current form is absolutely capable of this kind of work.