Summary
Matthew Berman shares results from early access to Sonnet 5.5, showing what Anthropic’s latest model can build from a single prompt, and where it falls short. The first demo is a real-time 3D ocean in the browser, with adjustable sea states, weather, time of day, a sailing yacht with a wake, and an underwater view with light shafts and fish. Sonnet also recorded and edited demo videos of the project on its own.
Other builds include a playable Fall Guys-style knockout game made with Three.js, where Berman says the model matched Opus 5.5. He stresses one prompting tip: explicitly tell the model to double-check its work with screenshots, video or by playing the game itself. A Lego web app converts text or images into models made of real parts, with step-by-step 3D instructions and exports such as PDF, BrickLink wanted lists, Rebrickable CSV and LDraw.
The video also revisits a downtown San Francisco simulation in Unreal Engine 5.8, with around 120,000 simulated people and 2,400 vehicles reacting to events, and compares the result with Opus 5.5. Berman notes the strengths, some clipping and performance issues, and the tradeoffs, making this a useful look at what current frontier coding models can do.
📺 Source: Matthew Berman · Published September 29, 2026
🏷️ Format: Showcase
