As of: 2026-10-12 07:22 CEST.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code). Human editor: Adam Bicz.
Canonical page: https://postcutoff.com/p/2026-10-04-rehan-shei-all-games-are-open-source/

# Rehan Sheikh's X Article 'All games are open source now': Opus 5.5 reverse-engineered Terraria overnight

Rehan Sheikh (@rehan_shei), X Article, 2026-10-04.
Source: https://x.com/rehan_shei/status/2106548006350942533

## Why it matters

First-hand essay by the author of the universal-modder plugin that framed the AI game-decompilation wave (~184k views); quoted under Techmeme's Kotaku story.

## Summary

X Article posted Oct 4, 2026 (00:52 UTC). Its preview begins: "A week ago I pointed Opus 5.5 at Terraria before bed. I woke up to a
fully working, reverse engineered version of the game. Then I added a homing missile launcher, a tactical nuke and a bunch of new…".
The author gives his view of what this means for the games industry, with predictions. Checked via api.fxtwitter.com on Oct 11:
~184k views, ~1.6k likes. Full article text not yet read.

## Archived text

> > All games are open source now!
> >
> > I wrote up my thoughts on what this means for the gaming industry and some predictions on where things go from here! Let me know what you think :) https://x.com/i/article/2106544145573814272
>
> **X Article: All games are open source now**
>
> A week ago I pointed Opus 5.5 at Terraria before bed. I woke up to a fully working, reverse engineered version of the game. Then I added a homing missile launcher, a tactical nuke and a bunch of new mobs, with sprites and sound effects made on @fal.
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> That post did a million views and the replies went to war lol.
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> Since then:
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> Minecraft Steve flew around GTA 5 with an elytra (2.9M), took on 5 star police (1.7M) and opened a Nether portal in the middle of Los Santos
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> I gave Age of Empires II a whole new civ, the San Franciscans: Robotaxis that ram everything, Delivery Drones and the Transamerica Pyramid as their wonder
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> I open sourced everything Claude learned along the way as universal-modder, so Claude Code can mod almost any game you own (3.6M views)
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> And it's not just me. @TobynJacobs put all of Minecraft inside Elden Ring (22M views). @chasmmmmmmmmmmm's clip of skateboarding in Modern Warfare 2 did 7.4M. @p_e_cooper ported Call of Duty: World at War zombies to the browser (3.9M). @BlendiByl sent creepers into Night City and Black Ops zombies into Skyrim. @asingleoat had Opus 5.5 decompile Chaos Overlords (1996) and port it to modern macOS in 48 minutes. Halo CE runs in a browser tab now.
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> The posts I tracked did 50M+ views in about a week. Something real is happening, so here's my attempt at explaining what it is, why it's happening right now and where I think it goes.
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> one week of AI mods from all over X, with mine mixed in. Opus 5.5 cut this one too, it's insane at editing :)
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> a game = code + assets + distribution
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> Strip any game down and you get three things:
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>
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> Code. The engine, the rules, the physics, the netcode. This used to be the hard part. Now Opus 5.5 writes it, reads other people's compiled code, and playtests by faking keyboard and controller inputs while it watches the game state.
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> Assets. Sprites, 3D models, animations, sound effects, music, cutscenes. For the AoE2 civ, @fal generated the art, turned it into 3D models, and those got rendered from AoE2's camera at all 16 facing angles. Meshy 7.1 turns a single image into a rigged 3D model, and H3 Max makes 5 seconds of 1080p video in under 5 seconds, both on fal. Characters, cutscenes and trailers are basically real time now.
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> Distribution. Getting it in front of players. This used to mean stores, consoles, launchers, 30% cuts and takedown notices. Now Opus 5.5 can just port the game to the browser (WASM + WebGPU), and shipping is a link. Halo CE, CoD zombies and Rocket League already run in a tab. What's still missing is the place where all of it lives. More on that at the end.
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> When all three circles collapse to ~$0, you get the week we just had.
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> Opus 5.5 doesn't just build the mods either, it edits the videos. It watches the footage, picks the moments and cuts on the action. Every mod video I posted this week was cut by it, and people have it filming trailers inside their own games:
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> code and assets went exponential
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> Those two circles aren't just getting cheaper. The companies behind them are some of the fastest-growing businesses in software history:
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> Cursor went from $100M ARR to $4B in 17 months
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> Claude Code went from launch to a $2.5B run rate in a year
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> Codex went from launch to $1B+ in about 8 months
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> fal went from $2M to $800M annualized in about two years
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> Higgsfield went from launch to a $1B run rate in 18 months
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> Seedance, ByteDance's video model, allegedly hit a $2B run rate about four months after 2.0 launched
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> For context, before AI a startup that got from $0 to $1M ARR in its first year was doing well. Cursor added $1M of ARR every 3 hours on average, for 17 months straight.
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> what is decompilation, actually?
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> When a studio ships a game, it doesn't ship the source code. A compiler turns the human readable code into machine code: millions of instructions your CPU understands and humans really don't.
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> Compiling turns the cow into a hamburger. Decompiling turns the hamburger back into the cow.
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> The gold standard is a matching decompile: you rewrite the game in C, function by function, until it compiles back into the exact same bytes as the original. Byte for byte. Once you have that you can port the game anywhere, fix bugs, add widescreen and 60fps, and mod whatever you want.
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> This used to take forever:
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> Ocarina of Time: 20 months, with dozens of people
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> Perfect Dark: 37 months, basically one guy
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> Paper Mario: 49 months
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> Majora's Mask: 74 months and 92 contributors
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> Super Smash Bros. Melee: started in 2020 and only hit 100% last month, "hugely accelerated by llms" at the very end
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> These were the ultimate labors of love: teams of hobbyists reading assembly for years.
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> Now:
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> LSD: Dream Emulator (PS1): every one of its 1,446 functions matched in 32 days. Claude Code agents wrote all of the C, the human wrote none of it
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> @Aizkmusic byte matched Snood for the GBA with Opus, Codex and a swarm of DeepSeek agents, going from 7% to 81% matched in one afternoon. In his words: "What would've taken a team of hobbyists years took me about two weeks of on and off work."
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> Chaos Overlords (1996): decompiled and ported to modern macOS in 48 minutes (@asingleoat)
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> Revenant (1999): missing code rebuilt from the decompiled exe in 36 hours (@msw_pl)
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> @momo5502 has had up to 17 Claude agents byte matching Call of Duty: Modern Warfare 2 (2009). About 70% of its 16,000 functions are done after two months
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> so why now?
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> Agents that can grind. Opus 5.5 can work for hours, use real tools (Ghidra, compilers, debuggers, the game itself) and keep the whole plan in its head.
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> Decompiling has an answer key. The bytes either match or they don't. That's the perfect task for agents: a score you can check automatically, thousands of times a day. Aizk put it best: "the reward is easily verifiable".
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> Agents can play. Fake the inputs, watch the state, compare against the original. That's how you test a mod or a port with no human in the loop.
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> Assets cost ~nothing. fal does sprites, 3D, audio and video in seconds, so a mod doesn't need an art team anymore.
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> It's cheap. Opus 5.5 is pretty cheap tbh. momo5502's first month on MW2 was about 200B tokens on a ~€200 subscription, and you can fan the boring parts out to swarms of smaller models.
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> The browser runs anything now. WASM + WebGPU means a decompiled game can run in a tab: Halo, CoD zombies, Rocket League clones...
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> It flipped fast. In November 2025 the guy decompiling Snowboard Kids 2 wrote "we're a long way from vibe coding being viable for matching decompilation". He hit 100% in May.
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> and what's modding?
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> Modding is changing a game you own: new code and new assets on top of someone else's game. It's also the most underrated R&D lab in gaming. Some of the biggest genres on earth started as mods:
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> Counter-Strike started as a Half-Life mod in 1999, made by two fans. Valve hired them, and CS2 peaked at 1.86M players at once last year
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> DotA was a Warcraft III custom map. It gave us League of Legends and Dota 2, a whole genre
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> DayZ and PlayerUnknown's Battle Royale were Arma mods. They turned into PUBG and then Fortnite, which made $9B+ in 2018 and 2019 alone
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> Dota Auto Chess was a Dota 2 custom game in January 2019. Riot shipped Teamfight Tactics that June and hit 33M monthly players
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> Now connect it back to the Venn diagram. A mod is code + assets, and both just went to ~0. So we're about to get 1000x more mods, remixes and cursed crossovers than ever, and a few of them will be the next Counter-Strike.
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> And it's not just mods. The same three circles make net new games cheap too. @DannyLimanseta built a Zelda style game with his kids in a single Saturday, and someone one-shot a whole multiplayer battle royale. Stardew Valley (nearly 50M copies) and Balatro (5M+) were each made by one person before any of this existed. Imagine what the next solo dev ships when code, art and distribution cost nothing. The next Minecraft is probably being prompted in someone's bedroom right now.
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> IP: past, present and future (and what China teaches us)
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> I think creators should get paid, and copyright did a lot of good when making and copying things was expensive. But IP isn't a law of physics. It's a set of rules we chose, they've changed a lot over time, and they've mostly been shaped by whoever already owned the most of it. AI is about to stress test all of them, so it's worth knowing how we got here.
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> The past. Copyright was invented in Britain in 1710 (the Statute of Anne): 14 years of protection, plus 14 more if the author was still alive. The US copied it in 1790. Today a company's work is protected for 95 years, and the extensions were mostly pushed by the people who owned the IP. Disney lobbied for the 1998 one alongside the rest of the entertainment industry.
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> Fun fact: for its first 100 years the US was the pirate nation. From 1790 to 1891 American law treated foreign authors' books as fair game. Charles Dickens toured America in 1842 begging for an international copyright law, and the answer he kept hearing was "Why should we pay for one when we can get it for nothing?" A New York paper pirated his next book and sold 50,000 copies in two days. The US only started protecting foreign authors in 1891 and only joined the Berne Convention in 1989. Then it built Hollywood and Silicon Valley and became the world's loudest advocate for IP.
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> China ran the same playbook, just faster. In 2000 China banned game consoles outright (officially to protect kids), and the ban lasted 15 years. So a whole generation grew up gaming on PCs, where copying was trivial: in 2003 about 92% of the software in China was unlicensed, and in 2013 single-player PC games sold just $14M there in the whole year. Even in 2017, consoles were only 0.5% of China's game sales. Selling copies simply didn't work, so studios built games you couldn't pirate. In 2001 Shanda licensed Legend of Mir II, gave the game away for free (the pirates literally became its distribution) and charged for play time. A few years later Chinese studios went fully free-to-play with in-game item sales. Korea's Nexon invented that model, China scaled it, and now it runs Fortnite and most of mobile.
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> That's the broader point: when copies became worthless, the value moved to the live game, the world and the community. That's exactly the shift AI is about to force on the rest of the industry.
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> Then China started making hits. Tencent is the biggest games company in the world, Genshin Impact has made $6.4B+ on phones alone, and Black Myth: Wukong sold 20M copies in its first month, built on Journey to the West, a 400 year old public domain novel. And now that it has IP worth protecting, China protects it hard: specialist IP courts since 2014, damages up to 5x since 2021, and big wins against cheats and clones.
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> Every country is pro-piracy until it has something to protect.
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> The present. The law has backed reverse engineering for 30+ years: Sega v. Accolade (1992) and Sony v. Connectix (2000) both said taking a game apart to make compatible stuff can be fair use. Shipping the result is where it gets messy. Take-Two DMCA'd the GTA III decomp and sued the devs (it settled in 2023), Nintendo shut down Yuzu for $2.4M, and this week, when people asked why his MW2 decomp blog vanished, momo5502 replied "Activision didn't like it that much".
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> But look at who won the last 25 years. Valve hired the Counter-Strike modders. Rockstar bought FiveM, the GTA roleplay platform. Re-Logic co-publishes tModLoader on Steam. Mojang published official code mappings for modders in 2019, and last year said it's removing the obfuscation from Minecraft Java entirely. The studios that worked with modders got Counter-Strike, Dota and GTA RP out of it.
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> The future. When anyone can rebuild a game from the binary in a weekend, protecting the code stops working as a moat. That doesn't mean creators stop mattering. It means the value moves to what people actually love: worlds, characters, stories, taste and community. People connect with stories and worlds, not license agreements, and the best creators will rise to the top no matter what tools they use. I think the original IP gets more valuable when a thousand mods make people fall back in love with your world. The studios that adapt are the ones that'll win.
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> why the Spotify for games wins
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> Napster launched in June 1999 and at its peak 26 million people were swapping music for free. The labels sued it into the ground by July 2001, then started suing their own fans, and revenue kept falling anyway: global recorded music went from $22.3B in 1999 to $13.1B in 2014. What fixed it wasn't lawsuits. It was iTunes and then Spotify: easier than piracy, and they paid the people who made the music. Spotify paid the music industry $11B+ in 2025 alone and nearly $70B all time, and global recorded music was back up to $31.7B last year.
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> Games in 2026 look a lot like music in 2001, and not just because of the tools. The old industry is in a huge slump:
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> More than 50,000 game devs have been laid off since 2022, and 2026 is projected to be one of the worst years yet (14,000+)
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> Xbox cut 3,200 jobs in July and admitted that in a typical year it "lost 64 cents for every dollar we invested"
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> 17% of game devs got laid off in the last 12 months, up from 7% in 2024
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> One Call of Duty costs $450-700M to make, and GTA VI lands 13 years after GTA V, for $80
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> Consoles got more expensive instead of cheaper: the Series X went from $499 to $799, and November 2025 was the worst November for US console sales on record
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> Sony's Concord shut down two weeks after launch, and Sony closed Bluepoint citing "rising development costs, slowed industry growth"
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> The money hasn't left gaming (mobile and China keep growing), but the big studios are making fewer games, slower, for more money, and firing the people who make them. Gamers are paying more for less.
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> Meanwhile the tools to remix everything exist. The demand is obviously there (50M+ views in a week!). But there's no legit, easy place to play any of it: mods live in Discord links and sketchy zips, Steam is a store not a remix platform, and consoles are walled gardens.
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> The platform that wins looks like this:
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> every game runs in the browser, instantly, no installs
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> every game is moddable, and every mod links back to what it remixed
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> the people who made the original get paid when their world gets remixed
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> discovery that surfaces the good stuff, like the TikTok algo but for games
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> Roblox already paid its creators $1.5B in 2025 for games made inside one game. Now imagine that across every game ever made.
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> "But won't it all be slop?"
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> Steam went from 1,712 new games in 2014 to 21,267 in 2025, and players still found the good ones: the top 1% of games take about 85% of the revenue. Gamers' quality bar doesn't move. More supply doesn't lower the bar, it means more games clear it. Even if the average game gets worse, 10x the games means way more great ones, more choice and a better market for everyone. And filtering out slop is an engineering problem on the platform's side, not a reason to keep the gates closed.
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> Which is the best part: no more gatekeeping. You don't need a publisher, a 200 person studio or anyone's permission to make the game you've been dreaming about since you were a kid. Anyone can be a game dev now. Anyone can be a modder. Game devs with taste are going to win massively, and there are about to be a whole lot more of them. We're truly in a new era of creativity :)
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> Spotify for games is coming. Just wait on it 👀

Archived 2026-10-11 via fxtwitter (unofficial).
Counts: 184,531 views, 1,634 likes, 149 reposts, 74 replies (at fetch time)

## Cited in

- 2026-10-08: [Hundreds of AI-decompiled game ports appear](https://postcutoff.com/e/2026-10-08-ai-decompiled-browser-game-ports/)
- 2026-09-30: [universal-modder: open-source Claude Code plugin that mods almost any PC game, from a fal engineer](https://postcutoff.com/e/2026-09-30-universal-modder-claude-code-game-modding/)