RAINY
TECH LAB
NEW Open for brand collaborations →ARTICLESIDEASLET’S TALK
AI & LLMs

I Asked Kimi K3.1 Pro to Build a 3D Game From One Prompt. It Worked. Here's the Catch

Kimi K3.1 Pro is the new flagship model from Moonshot AI, the Chinese lab behind Kimi. It launched on October 23, 2026.

By Rainy3 min read

AI-assisted disclosure: I used an AI assistant to help structure this write-up. The test runs, timings and logs are my own (kimi.ai free plan, October 28, 2026). Benchmark numbers come from Moonshot's blog and Artificial Analysis, linked at the end.

Short version: one prompt to Kimi K3.1 Pro gave me a playable 3D racing game: a single 752-line HTML file using Three.js, 3 laps, 60 fps, zero page errors. But the file took about 21 minutes to arrive, Kimi's own self-test was still stuck after 38 minutes, and the free plan refused my next prompt 6 times in a row.

▶ WATCH ON YOUTUBEWatch the video ▶ WATCH ON YOUTUBEFull video

What is Kimi K3.1 Pro?

Kimi K3.1 Pro is the new flagship model from Moonshot AI, the Chinese lab behind Kimi. It launched on October 23, 2026.

  • Base model: Kimi K3, about 2.8 trillion parameters (mixture of experts)
  • Context window: 1 million tokens
  • Open weights: Moonshot says the full weights will be released by November 4, 2026
  • API price: $2 input / $10 output per million tokens ($0.20 for cached input). A Highspeed variant costs $4 / $20.

Moonshot's headline claim is that it codes almost as well as Claude Opus 5.5. I wanted to see what a normal person gets on the free website.

Test 1: one prompt, one 3D game

This is the exact prompt I sent on kimi.ai (free plan, Kimi K3.1 Pro):

Build a playable 3D racing game in ONE single HTML file using Three.js from a CDN.
Low-poly neon city track at night, the car drives with WASD or arrow keys, chase
camera, 3 laps with a lap timer and best-lap display, a few obstacles to dodge,
and a start screen with "Press Space". No other external assets. Give me the full file.

Kimi came back with "Neon Velocity": one index.html, 752 lines, 47 KB, Three.js loaded from a CDN, a night circuit, nitro, a minimap, lap timers and a finish screen.

To check it honestly, I didn't just eyeball it. I drove it with a script that sends real key presses in headless Chrome on a Mac mini M4:

title screen ready            0.16 s
lap 1 done                    19.533 s
lap 2 done                    41.033 s
race finished                 64.750 s (shown as 1:04.749)
best lap                      0:19.516
fps                           avg 60.5, min 60
page errors                   0
draw calls / triangles        36 / 25,554

The only console message was a Three.js warning about the old non-module build. For a single prompt, that is a genuinely good result.

Test 2: speed

This is where it hurt.

  • The file was written about 21 minutes after I hit send.
  • Kimi then tried to test the game itself in its own browser. It hit a 404 on its own server, switched ports, and its step "Loads game and captures title screen" was still running at 38:53. I stopped it and took the file from the chat.

Artificial Analysis measured the API at about 42.7 tokens per second (No. 184 of 192 models) when I checked, versus about 98 for Claude Opus 5.5.

Test 3: the free plan

Next I asked for a second round: 3 AI rival cars and a race position display. The free plan refused it 6 out of 6 times, including in a brand-new chat and at a lower effort setting:

"Too many people are chatting with Kimi; a subscription will grant you priority access."

So "free" works, but not reliably during busy hours. On the API side it is cheap: Artificial Analysis lists about $3.68 to run its index tasks on Kimi K3.1 Pro versus $10.04 on Opus 5.5.

Test 4: is it really Opus-level?

Source Kimi K3.1 Pro Claude Opus 5.5
Moonshot (self-reported): Terminal-Bench 4.0 65.7% 66.4%
Moonshot (self-reported): BenchCAD 92.7% 96.2%
Artificial Analysis: Intelligence Index 46 (No. 20 of 51) 58

On Moonshot's own chart it's less than a point behind. The independent index puts it well behind, in 20th place. Both can be true: it is very strong at the agentic coding tasks Moonshot picked, and less strong across the board.

The catch

  • Slow. 21 minutes for one file, plus a self-test that never finished.
  • The free plan gets busy. 6 of 6 follow-up prompts refused.
  • "Opus-level" is Moonshot's claim, not the independent ranking.

Verdict

If you want the best coding model today, Claude Opus 5.5 is still smarter and more than twice as fast. But one free prompt built a real, playable 3D game, and the API is about a third of the price. If the open weights really land by November 4, anyone with enough GPUs can run a near-frontier model themselves. That's the part I'll be watching.

Have you tried Kimi K3.1 Pro for coding yet? I'd like to know if you hit the same free-plan wall.

Sources

I Pointed Craft Anything at Hacker News. Claude Code Rebuilt It 91% Without Me Writing a Line

It's a desktop app from storytold, the team behind ArtCraft. You point it at a website, app or game, and say what you want.

· 3 MIN READ

Claude Opus 5 Built a Full-Stack App From One Prompt: 64/64 Tests and 3 Invented Package Versions

Instead of reading benchmark charts, I gave Claude Opus 5 an empty folder and one prompt: build a full-stack app. I didn't write any of the application code.

· 4 MIN READ

I Let OpenAI Codex Build My Website From One Prompt: 5 Minutes 23 Seconds, 12/12 Checks

I gave OpenAI's Codex one prompt, an empty folder and a hard 15-minute limit to build a real personal website for my YouTube channel.

· 7 MIN READ