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welp. i had one of those rare fall off your chair moments yesterday working with codex + our newest model gpt-5.3-codex.
20ish turns and 33,082 tokens later. here's the result: alistairtown.vercel.app 🤯
🧵
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alistair
259 posts
alistair
@hellodzzy
applied evals @openai cleaning @nyc_taipans
Brooklyn, NY Joined Mart 2018
449 Following349 Followers
alistair retweeted
We’re launching Codex for Open Source to support the contributors who keep open-source software running.
Maintainers can use Codex to review code, understand large codebases, and strengthen security coverage without taking on even more invisible work.
developers.openai.com/codex/communit…
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alistair retweeted
GPT-5.4 is here.
Native computer-use capabilities.
Up to 1M tokens of context in Codex and the API.
Best-in-class agentic coding for complex tasks.
Scalable tool search across larger ecosystems.
More efficient reasoning for long, tool-heavy workflows.
openai.com/index/introduc…
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alistair retweeted
Big Update Coming to the Unity Game Engine for AI Game Development
- The company will unveil a beta of a upgraded Unity AI that lets developers prompt full "casual" games into existence using only natural language
- This AI assistant will be powered by Unity’s understanding of the project context and runtime, while leveraging the best frontier models that exist
- The beta reveal is scheduled for GDC on March 12, 2026
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@kleneway is one of the best model whisperers we have. it's super fun learning how he goes about maximizing model performance on a range of cool tasks.
Kevin Leneway@kleneway
🏂❄️ Ski Jump Simulator 🏂❄️ This was my first real wow moment with the new Codex app + skills + codex-5.3. I was able to ship a playable, physics-based sim even though I’ve never built a game before! 🧵on tips / lessons learned ski-jump-sim.vercel.app
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alistair retweeted
🏂❄️ Ski Jump Simulator 🏂❄️
This was my first real wow moment with the new Codex app + skills + codex-5.3. I was able to ship a playable, physics-based sim even though I’ve never built a game before!
🧵on tips / lessons learned
ski-jump-sim.vercel.app
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There's something mesmerising about staring at procedurally generated Diablo-style items with affixes and rarities.
I had to vibe code a custom art generation tool to make consistent art for this game. It's not perfect but it's getting there.
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1000 tokens/second 👀
OpenAI@OpenAI
GPT-5.3-Codex-Spark is now in research preview. You can just build things—faster.
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Huge for legacy software in large enterprise 👀
Sherwin Wu@sherwinwu
Been seeing more and more crazy examples of people porting software over to new languages or platforms with GPT-5.3-Codex – a friend said he used Codex to rewrite the Codex app to work on Linux over the weekend. But this one is particularly cool – SimCity in Typescript!
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alistair retweeted
many of the example use codex desktop with the imagegen and playwright skills installed so that codex can both generate assets and review its works.
for intricate assets, like my own sprite, i leaned on imagegen in ChatGPT so I could be in the loop for making my asset sheets. imagegen certainly isn’t perfect but it’s enough to build something cool that works.
x.com/hellodzzy/stat…
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For those saying @OpenAI GPT-5.3 Codex can generate game asset images on its own and build games end-to-end with zero human work: HOW?
It just reaches for random third-party image APIs instead of doing it on its own.
Am I missing something? I'm on gpt-5.3-codex-extrahigh
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alistair retweeted
Built a three js multiplayer counter strike with Codex 5.3 in two days, played with friends
- Use Colyseus networking engine + collisions
- Physics engine w accurate projectiles
- Physically based sky (takram atmos)
- Physically based materials (aniso, dispersion etc)
- Soft body collisions, water, cloth, instancing sims
- Bloom, SSAO/HBAO (opt), SSGI, motion blur, DOF
- Explosions and procedural destruction
- Spatial sounds and music (incl procedural too)
- Procedural level creation (llm+kitbash+bot/navmesh+latest papers on the subject)
- Custom game editor w Codex cli built in and more...
Codex 5.3 built everything, including the game editor itself and custom tooling. I just started from a boilerplate three js FPS called "notstrike"
I am not a dev
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@cocktailpeanut generate your game art in parallel and iterate. once the game mechanics are down, the fun begins.
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> Hey GPT-5.3 Codex, make me a Tekken game
15 minutes later...
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the moment the sprites are set. feature velocity.
prashant@prashantmital
gpt-5.3-codex is the best coding model we’ve ever shipped. but here’s the honest take: when you’re still feeling your way through an idea — half-formed vision, messy repo, vibes > architecture — it can feel unhelpfully literal. it needs existing structure. that “downside” turns into a superpower the moment the rails are set. feature velocity. refactors. bug hunts. edge-case hardening. test coverage >>> the kind of professional SWE work that normally requires an agency.
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