Fable 5.1 Is Absurd.

Summary
In this video, creator LanceyPoo tests Anthropic’s Claude Fable 5.1 using the Claude Code desktop interface set to "Ultra-code" effort. He feeds the model three single-shot prompts to build complete 3D web games in Three.js from scratch—clones of Minecraft, Garry's Mod, and Super Mario 64 (Bob-omb Battlefield)—and plays through each generated result in his browser.

What is shown

• [00:03] Benchmark table: A comparison slide showing Claude Fable 5.1 benchmark scores alongside Fable 5, Opus 5, and GPT-5.6 Sol across tests like Terminal-Bench, GDPval-AA v2, OSWorld 2.0, Humanity's Last Exam, and CursorBench 2.0.
• [00:20] Claude Code UI & Setup: Setting the model selector to Fable 5.1 and bumping effort level to "Max / Ultra-code".
• [00:42] Minecraft Clone ("HEWN"): Generated in approximately one hour; features procedurally generated voxel terrain with mountains and caves, passive mobs with faces, flying/creative mode, block picking and building (constructing a wooden hut with glass windows and torches), fluid/water placement, and survival mode with block durability and functional recipe crafting (planks, crafting table, wooden pickaxe).
• [03:24] Garry's Mod Clone ("CONSTRUCT"): Generated in about 40 minutes; features a physics sandbox map, a physics gun (grabbing, freezing, rotating, and throwing objects), a spawn menu with props (pallets, barrels, furniture, crates), and tool guns (weld gun, thrusters, wheels). Lance builds a thruster-powered pallet craft and a motorized/flying refrigerator vehicle.
• [07:22] Super Mario 64 Recreation (Bob-omb Battlefield): Generated in about 45 minutes; features third-person movement, jumping, long jumps, backflips, red coin collection, functional cannons aiming to the floating island, Goombas, an interactive Bob-omb buddy, a functioning King Bob-omb boss fight (picking up and throwing the boss three times to receive a Power Star), and pounding down the wooden post to release the Chain Chomp.

Claims & numbers

• The presenter displays a table listing Claude Fable 5.1 benchmark results: Terminal-Bench-Science 0.1 (52.6%), Terminal-Bench 4.0 (55.8%, with Mythos 5.1 at 60.9%), GDPval-AA v2 (1853), OSWorld 2.0 (77.9% partial / 41.7% strict), Humanity's Last Exam (60.9% no tools / 65.0% with tools), AutomationBench (31.4% with tools), and CursorBench 2.0 (73.4%).
• The presenter claims the Minecraft clone was generated in 1 hour from a single prompt [00:40].
• The presenter claims the Garry's Mod sandbox was generated in 40 minutes from a single prompt [03:23].
• The presenter claims the Super Mario 64 recreation took 45 minutes to complete [07:21].
• The presenter awards Fable 5.1 a "9.9 out of 10" for the Minecraft output [02:58].

Notable quotes

• [01:00] "This is the most insane Minecraft clone from one-shot I've ever seen in my entire life."
• [03:00] "One single prompt gets you a game so close to Minecraft... this is so crazy."
• [06:54] "Yeah, dude, this was the greatest one-shot prompt we've seen so far."

Assessment
This is a third-party developer review and hands-on demonstration testing the coding capabilities of Claude Fable 5.1 under its Ultra-code setting. The generation wait times (40 to 60 minutes each) are edited out, but the resulting web applications are fully demonstrated in real-time gameplay showing genuine interactive mechanics and functional 3D rendering.

Described by gemini-3.8-flash on 2026-09-29 from the video's audio and frames.