As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/v/yt-lanceypoo-fable-5-1-is-absurd/

# Fable 5.1 Is Absurd.

LanceyPoo, 8 September 2026, YouTube. 150,149 views as of 6 November 2026.
Kind: Community.
Watch: https://www.youtube.com/watch?v=sjp2yCkHyK4

## Why it is here

Found 2026-09-29 by YouTube search "claude fable 5.1" (sorted by upload date). Listed as: 149,176 views, length 10:03, published "3w ago" (so the date above is approximate).

## Description (written by Gemini from the video)

**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._

## How AI was used to make it

AI made most of it of this video (Subject built by AI).
- Claude Fable 5.1 single-shot generated Three.js 3D games (Minecraft, Garry's Mod, Super Mario 64 clones)
Tools: Claude Fable 5.1, Claude Code
(Classified by gemini-3.8-flash from our description; high confidence. Overview: https://postcutoff.com/ai-video/)

## Related

- 2026-09-01: [Anthropic releases Claude Fable 5.1 and Claude Mythos 5.1](https://postcutoff.com/e/2026-09-01-claude-fable-5-1-mythos-5-1/)

## More videos on this

- 2026-10-12: [GPT-6 ASTRA vs CLAUDE FABLE 5.1 (INSANE CHESS MATCH)](https://postcutoff.com/v/gothamchess-gpt-6-astra-vs-claude-fable-5-1-chess-match/), GothamChess, YouTube, community, 3,555,251 views as of 6 November 2026.
- 2026-09-03: [A villa scene built in Blender by Fable 5.1 and GPT-6 Astra](https://postcutoff.com/v/karankendre-fable-5-1-gpt-6-astra-villa-blender-x/), Karan (@karankendre), X, made by AI, 2,891,697 views as of 8 November 2026.
- 2026-09-01: [Fable 5.1 designs a house for a lot, renders it and makes a cinematic walkthrough](https://postcutoff.com/v/alexalbert-fable-5-1-house-walkthrough-x/), Alex Albert (@alexalbert__), X, made by AI, 1,297,068 views as of 8 November 2026.
- 2026-10-02: ["I asked for a dot. Fable 5.5 gave me a Pixar side quest": a red dot bounces through hills and stars](https://postcutoff.com/v/cherry-mx-reds-fable-5-5-dot-pixar-side-quest-x/), Tak (@cherry_mx_reds), X, made by AI, 856,494 views as of 29 October 2026.

What else happened that month, day by day: https://postcutoff.com/timeline/2026/09/