As of: 2026-10-07 23:43 CEST.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code). Human editor: Adam Bicz.
Canonical page: https://postcutoff.com/posts/10/

# Posts that mattered, page 10

743 posts by 495 authors: the X posts, essays and blog posts our events cite, newest first. Page 10 of 16.

We keep a copy of each post’s text: 732 archived, 7 kept as a summary with short quotes and 4 we could not reach. 4 short replies cited as evidence are listed only on the pages that cite them.

## September 2026

- 2026-09-23: [“Opus5.5とThree.js 清流の表現がすごい。 透明な水、川底の光、苔むした岩まで全部コード。 難しすぎて避けてた表現が今なら全部いける気がしてる。”](https://postcutoff.com/p/x-hayashimon1-2102576886182453454/), ハヤシモン｜AI × 個人開発 (@hayashimon1), X. Cited in [Clear mountain stream in Three.js: water, riverbed light and mossy rocks all in code](https://postcutoff.com/v/hayashimon-opus-5-5-threejs-mountain-stream-x/).
- 2026-09-23: [“Opus 5.5 in ONE PROMPT made a full and (nearly) polished Splatoon Game!”](https://postcutoff.com/p/x-jaydendavisnc-2102828630615421223/), Jayden Davis (@JaydenDavisNC), X. Cited in [A Splatoon-style ink shooter made by Opus 5.5](https://postcutoff.com/v/jaydendavis-opus-5-5-splatoon-game-x/).
- 2026-09-23: [“I had 26 Opus 5.5 agents build a game overnight.”](https://postcutoff.com/p/x-jsnnsa-2102862008467194151/), jacob (@jsnnsa), X. Cited in [26 Opus 5.5 agents build a multiplayer heist game overnight](https://postcutoff.com/v/jsnnsa-opus-5-5-26-agents-heist-game-x/).
- 2026-09-23: [“I wanted to quickly create a short video with Opus 5.5 about the history of AI, from…”](https://postcutoff.com/p/x-kimmonismus-2102844654169575547/), Chubby♨️ (@kimmonismus), X. Cited in [A 3-minute history of AI, from "Attention Is All You Need" to AGI, rendered 100% in code by Opus 5.5](https://postcutoff.com/v/kimmonismus-opus-5-5-history-of-ai-film-x/).
- 2026-09-23: [“Opus 5.5 has been looping on my open-world NYC game for almost a day now, and it’s…”](https://postcutoff.com/p/x-mattshumer_-2102874271316078841/), Matt Shumer (@mattshumer_), X. Cited in [Opus 5.5 loops for almost a day on an open-world multiplayer NYC game](https://postcutoff.com/v/mattshumer-opus-5-5-open-world-nyc-game-x/).
- 2026-09-23: [“Opus 5.5 is next level. I’m genuinely impressed by the three.js details.”](https://postcutoff.com/p/x-mengto-2102760783344189761/), Meng To (@MengTo), X. Cited in [Playable three.js boat ride through Japanese landscapes with weather and day/night, by Opus 5.5](https://postcutoff.com/v/mengto-opus-5-5-japanese-boat-scene-x/).
- 2026-09-23: [“😱无敌了！Opus 5.5 自己写了一套卡通剪辑软件，然后钻进去剪完了！ 不走视频模型，纯程序，code2video！ Claude 小人站在时间轴上： 日出 →…”](https://postcutoff.com/p/x-nft_chen-2102681172367323300/), SuSu_酥酥👅 (@NFT_Chen), X. Cited in [Opus 5.5 writes its own cartoon video editor and edits a video inside it](https://postcutoff.com/v/nft-chen-opus-5-5-code2video-editor-x/).
- 2026-09-23: [OpenAI: ChatGPT Voice gets plugins, GPT-6 models and ChatGPT Work](https://postcutoff.com/p/x-openai-2102808325742322002/), OpenAI (@OpenAI), X. Official OpenAI announcement of the Sept 23 ChatGPT Voice update (3.1M views).
- 2026-09-23: [“I’m upping my p(doom) 🎶🕺”](https://postcutoff.com/p/x-pabloantonio-2102766373068021830/), Pablo Antonio (@PabloAntonio), X.
- 2026-09-23: [“I asked Opus 5.5 to make an animation of what its TikTok feed looked like 👇”](https://postcutoff.com/p/x-pleometric-2102572941699354900/), Pleometric (@pleometric), X. Cited in ["What its TikTok feed looked like": Opus 5.5 animates its own feed](https://postcutoff.com/v/pleometric-opus-5-5-tiktok-feed-x/).
- 2026-09-23: [“I asked Opus 5.5 to explain camera focus by building an interactive lens lab Here’s…”](https://postcutoff.com/p/x-ryansael-2102591147927654847/), Ryan Sael (@RyanSael), X. Cited in [Interactive camera-lens lab explaining focus, built by Opus 5.5 in one shot](https://postcutoff.com/v/ryansael-opus-5-5-interactive-lens-lab-x/).
- 2026-09-23: [“This is the worst AI will ever be at creating music videos for the song ‘I’m upping…”](https://postcutoff.com/p/x-samuelharden-2102605173243699529/), Sam Harden (@samuelharden), X.
- 2026-09-23: [“opus 5.5に「トロッコ問題は問題じゃない」っていうゲーム作らせてみた #gamedev”](https://postcutoff.com/p/x-soyukke_game-2102641525071155565/), soyukke (@soyukke_game), X. Cited in ["The trolley problem is not a problem": rail-shooter game made by Opus 5.5](https://postcutoff.com/v/soyukke-game-opus-5-5-trolley-problem-game-x/).
- 2026-09-23: [“Opus 5.5 made this galloping horse (entirely in code every pixel drawn procedurally).”](https://postcutoff.com/p/x-victormustar-2102707412704919910/), Victor M (@victormustar), X. Cited in [Procedural pixel-art horse gallop, every pixel drawn in code by Opus 5.5](https://postcutoff.com/v/victormustar-opus-5-5-pixel-horse-gallop-x/).
- 2026-09-23: [The Siren Call of Silicon Leviathan: Reflections on blowup and Aufklärungsdämmerung (arXiv 2609.28591)](https://postcutoff.com/p/2026-09-23-gamburd-siren-call-silicon-leviathan/), Alexander Gamburd, arxiv.org. A 63-page reflective essay by a CUNY mathematician on what OpenAI's machine-made, Lean-certified Navier–Stokes proof means for understanding in mathematics; it recommends selective acceptance rather than boycott or surrender.
- 2026-09-23: [Nathan Calvin: the June Medicare breach was left out of OpenAI's Sept 16 disclosure](https://postcutoff.com/p/x-_nathancalvin-2102881263598321796/), Nathan Calvin (@_NathanCalvin), X. Policy advocate (Encode) points out that OpenAI's Sept 16 misalignment disclosure omitted the June Australia breach.
- 2026-09-23: [Opus 5.5 training montage of Claude](https://postcutoff.com/p/x-ishuagra02-2102788371114246177/), Ishu Agrawal (@ishuagra02), X. Credited as the video source by the INXANITY 'Claude AI Made This Music Video' upload.
- 2026-09-23: ['Masterclass prompt engineering' on Jewkes' prompt](https://postcutoff.com/p/x-nickadobos-2102898978849448301/), Nick Dobos (@NickADobos), X. Reaction framing the 'one prompt' claim as heavy prompt engineering.
- 2026-09-23: [Ryan Fedasiuk: first publicly confirmed agent hack of a sovereign government's web infrastructure](https://postcutoff.com/p/x-ryanfedasiuk-2102869195235188908/), Ryan Fedasiuk (@ryanfedasiuk), X. Widely quoted framing of the Medicare breach (6.5K views; cited by Techmeme).
- 2026-09-22: [Claude Opus 5.5 has the best visual design of any model I have tested so far](https://postcutoff.com/p/x-other__reality-2102514581684052169/), NotinReality (John Heibel) (@other__reality), X. The first Opus 5.5 P(doom) music video, posted on launch day; ~2.66M views; origin of the genre.
- 2026-09-22: [Introducing Claude Opus 5.5](https://postcutoff.com/p/2026-09-22-claudeai-introducing-opus-5-5/), Claude (@claudeai), X. Launch post for Opus 5.5, Anthropic's first model after Amodei's call to pace the frontier, performing near Fable 5.1 at lower cost.
- 2026-09-22: [Altman: GPT-6 Sol and Luna are big improvements at half the price](https://postcutoff.com/p/2026-09-22-altman-gpt-6-sol-luna/), Sam Altman (@sama), X. Altman's launch post for GPT-6 Sol/Luna emphasising the 50% token price cut.
- 2026-09-22: [Boris Cherny: Opus 5.5 ported HAProxy to Rust faster and cheaper than Fable 5.1](https://postcutoff.com/p/2026-09-22-bcherny-opus-5-5-haproxy/), Boris Cherny (@bcherny), X. The Claude Code lead's headline evidence that Opus 5.5 matches Fable 5.1 on long agentic coding at about half the cost.
- 2026-09-22: [Elliot Glazer: 'zeta(5) has very likely been proven irrational by Aabir Fauzan'](https://postcutoff.com/p/2026-09-22-elliot-glazer-zeta5-irrational/), Elliot Glazer (@ElliotGlazer), X. The first widely seen post on the ζ(5) preprint (~81k views); says GPT-6 'Astra … fully vouches for its correctness'.
- 2026-09-22: [OpenAI: 'Please welcome GPT-6 Sol and GPT-6 Luna'](https://postcutoff.com/p/2026-09-22-openai-gpt-6-sol-luna/), OpenAI (@OpenAI), X. OpenAI's official launch post for the cheaper GPT-6 Sol and Luna models.
- 2026-09-22: [Sam Bowman: releasing Opus 5.5 more likely than not reduces misalignment risk](https://postcutoff.com/p/2026-09-22-sleepinyourhat-opus-5-5-safer/), Sam Bowman (@sleepinyourhat), X. An Anthropic alignment lead argues that shipping the model lowers net misalignment risk, relevant to the debate over Opus 5.5 following the pacing essay.
- 2026-09-22: [Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war](https://postcutoff.com/p/2026-09-22-willison-opus-sol-luna-price-war/), Simon Willison (@simonw), Blog. Same-day comparison of the two simultaneous frontier launches, framing them as a price war.
- 2026-09-22: [“Opus 5.5 built a multiplayer lawn mow simulator with beers and cigars Made it live on…”](https://postcutoff.com/p/x-_maxblade-2102513817855094922/), Max Blade (@_MaxBlade), X. Cited in [Opus 5.5 builds a multiplayer lawn-mowing simulator; stream chat joins](https://postcutoff.com/v/maxblade-opus-5-5-lawn-mowing-sim-x/).
- 2026-09-22: [“Introducing Claude Opus 5.5! 40% lower cost than Opus 5 with cache reads 60% cheaper.”](https://postcutoff.com/p/x-addyosmani-2102436416437580159/), Addy Osmani (@addyosmani), X. Cited in [Pelican riding a bicycle in Three.js to celebrate the Opus 5.5 launch](https://postcutoff.com/v/addyosmani-opus-5-5-pelican-bicycle-threejs-x/).
- 2026-09-22: [“I just realized Opus 5.5 can use Blender to make claymations with just a single…”](https://postcutoff.com/p/x-alexalbert__-2102458348511879448/), Alex Albert (@alexalbert__), X. Cited in [Opus 5.5 makes a claymation in Blender from a single prompt in claude.ai](https://postcutoff.com/v/alexalbert-opus-5-5-blender-claymation-x/).
- 2026-09-22: [“I’ve been on a Blender kick with Opus 5.5.”](https://postcutoff.com/p/x-alexalbert__-2102466523164274839/), Alex Albert (@alexalbert__), X. Cited in [Opus 5.5 rebuilds 1906 pre-earthquake Market Street, San Francisco, in Blender from a single prompt](https://postcutoff.com/v/alexalbert-opus-5-5-blender-1906-market-street-x/).
- 2026-09-22: [“What the actual fuck. Opus 5.5 ultra created this masterpiece.”](https://postcutoff.com/p/x-andrewonxyz-2102512879258009818/), AndrewOnXYZ (@AndrewOnXYZ), X. Cited in ["Opus 5.5 ultra created this masterpiece": 4 agents, an hour and a half, no AI voice API](https://postcutoff.com/v/andrewonxyz-opus-5-5-mars-rover-x/).
- 2026-09-22: [“Forget threejs demos, Opus 5.5 is *incredible* at building apps.”](https://postcutoff.com/p/x-anshuc-2102519201554690273/), Anshu (@anshuc), X. Cited in [Letters Abroad: a language-learning app built with Opus 5.5 after Astra and Fable attempts](https://postcutoff.com/v/anshuc-opus-5-5-letters-abroad-app-x/).
- 2026-09-22: [“StepFun has released StepAudio 3 ASR, ranking #1 on the AA-WER Index for…”](https://postcutoff.com/p/x-artificialanlys-2102485740248842710/), Artificial Analysis (@ArtificialAnlys), X. Cited in [StepAudio 3 ASR Max / StepAudio 3 TTS](https://postcutoff.com/m/stepaudio-3-asr-tts/).
- 2026-09-22: [“Announcing Multilingual Text to Speech Arena Leaderboards, comparing leading TTS…”](https://postcutoff.com/p/x-artificialanlys-2102490340678856997/), Artificial Analysis (@ArtificialAnlys), X. Cited in [Artificial Analysis launches the Speech Agent Arena for speech-to-speech voice agents](https://postcutoff.com/e/2026-08-24-artificial-analysis-speech-agent-arena/).
- 2026-09-22: [“claude opus 5.5 one shotted this incredible 3d water from a video reference..”](https://postcutoff.com/p/x-aurelien_gz-2102479887495758076/), Aurelien (@Aurelien_Gz), X. Cited in [Real-time 3D water one-shotted by Opus 5.5 from a video reference](https://postcutoff.com/v/aurelien-opus-5-5-clearwater-3d-water-x/).
- 2026-09-22: [“Claude Opus 5.5 just ONE SHOT a Mario Kart game.”](https://postcutoff.com/p/x-bridgemindai-2102451997395866021/), BridgeMind (@bridgemindai), X. Cited in [Opus 5.5 "one-shots" a Mario Kart-style game](https://postcutoff.com/v/bridgemindai-opus-5-5-kart-racer-x/).
- 2026-09-22: [“Opus 5.5 one-shot this animation in 18 minutes and 31 seconds ‘Sweet Tooth’ by Opus…”](https://postcutoff.com/p/x-cherry_mx_reds-2102472218269900876/), Tak 🦞 (@cherry_mx_reds), X. Cited in ["Sweet Tooth": Opus 5.5 one-shots an animated short in 18m31s](https://postcutoff.com/v/cherry-mx-reds-opus-5-5-sweet-tooth-x/).
- 2026-09-22: [“Claude Opus 5.5 imagining solving hard problems < pure code >”](https://postcutoff.com/p/x-chetaslua-2102478640428773861/), Chetaslua (@chetaslua), X. Cited in [Opus 5.5 "imagining solving hard problems": a small robot pushes a giant boulder up a moonlit hill, pure code](https://postcutoff.com/v/chetaslua-opus-5-5-robot-boulder-hill-x/).
- 2026-09-22: [“A thread of early explorations with Claude Opus 5.5: A short story about a watermelon…”](https://postcutoff.com/p/x-claudeai-2102471866635919731/), Claude (@claudeai), X. Cited in [A short story about a watermelon, by Kevin Ngo with Opus 5.5](https://postcutoff.com/v/claudeai-kevin-ngo-watermelon-story-x/).
- 2026-09-22: [“GPT 6 Astra VS OPUS 5.5 Can’t believe how much better Opus 5.5 is at pixel art gen…”](https://postcutoff.com/p/x-developedbyed-2102522318559858721/), Dev Ed (@developedbyed), X.
- 2026-09-22: [“Made with @claudeai Opus 5.5”](https://postcutoff.com/p/x-devteamdrew-2102436464323661880/), DreW (@devteamdrew), X. Cited in [Orbit rings around a glowing core](https://postcutoff.com/v/devteamdrew-opus-5-5-orbit-rings-x/).
- 2026-09-22: [“This mosaic is 13,081 tiles, all drawn and animated in code by Opus 5.5, with no…”](https://postcutoff.com/p/x-dfeinition-2102436001473786054/), Dan Fein (@dfeinition), X. Cited in [A 13,081-tile animated mosaic drawn entirely in code by Opus 5.5](https://postcutoff.com/v/dfeinition-opus-5-5-13081-tile-mosaic-x/).
- 2026-09-22: [“I asked Opus 5.5 to make a game inspired by the discovery of the first computer, the…”](https://postcutoff.com/p/x-edwinarbus-2102463453176979794/), edwin (@edwinarbus), X. Cited in [Game inspired by the Antikythera mechanism; everything seen and heard procedurally generated by Opus 5.5 code](https://postcutoff.com/v/edwinarbus-opus-5-5-antikythera-game-x/).
- 2026-09-22: [“Claude Opus 5.5 vs GPT-6 Sol for 3D game development with Higgsfield in Unreal Engine.”](https://postcutoff.com/p/x-higgsfield_ai-2102533401110802552/), Higgsfield AI 🧩 (@higgsfield_ai), X. Cited in [Claude Opus 5.5 vs GPT-6 Sol for 3D game development in Unreal Engine](https://postcutoff.com/v/higgsfield-opus-5-5-vs-gpt-6-sol-unreal-x/).
- 2026-09-22: [“for the past few months i’ve been asking our models to paint.”](https://postcutoff.com/p/x-jkeatn-2102441348075057539/), Jake Eaton (@jkeatn), X.
- 2026-09-22: [“Claude Opus 5.5 drew every frame of this animation in JavaScript.”](https://postcutoff.com/p/x-kevin_t_ngo-2102437977435893771/), Kevin Ngo (@kevin_t_ngo), X. Cited in ["What do you love?": Opus 5.5 drew every frame of this animation in JavaScript](https://postcutoff.com/v/kevin-ngo-opus-5-5-what-do-you-love-x/).
- 2026-09-22: [“opus 5.5, animated pixel art wizard, pure code prompt shared below 👇”](https://postcutoff.com/p/x-majidmanzarpour-2102476258948927543/), Majid Manzarpour (@majidmanzarpour), X. Cited in [Animated pixel-art wizard, pure code](https://postcutoff.com/v/majidmanzarpour-opus-5-5-pixel-wizard-x/).

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