Real head-to-head · same prompt, one shot
Fugu Mini vs Claude Opus 5.5
Fugu's fast mini variant — single model, no panel, ~3 min per build. vs Anthropic's Opus 5.5 — benched on all 50 one-shot builds, every game playtested.
Head-to-head verdict: Claude Opus 5.5 wins 18–17 with 1 tie.
What I tested — same prompt, two models
I run the same fixed prompt set through every new model the day it drops — same string, one shot, single HTML file out — and I score the result 0–10 on whether it ran, how close it hit the brief, and how good it looked. Below is what came out when I gave the exact same prompts to Fugu Mini and Claude Opus 5.5, side by side, on 37 shared tasks inside the Agent Operating System.
Both models were given identical prompts inside the Agent Operating System — no help, no iteration, no "best of N" tricks. I run each prompt once, save the HTML file the model produces, and score it 0–10 on whether it ran, how close it hit the brief, and how good it looked. The scoring is mine. The verdicts below are pulled from my source comparison guides at agentos.guide where I publish every score and the reasoning behind it.
Fugu Mini · Dispatched from Agent OS as the fast Sakana lane. Bench scored by Claude judge against the same 42 prompts.
Claude Opus 5.5 · Benched on all 50 GoldieBench tasks via a Claude subscription: one-shot builds, real renders, pixel-diff playtests on every game, then vision-judged.
Side-by-side on 50 shared tasks
Click any cell to play that model's actual one-shot attempt. Medals are derived from my 0–10 scores per task (highest = 🥇, second = 🥈, third = 🥉).
Task ↓
Fugu Mini
Claude Opus 5.5
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Game
Page
Page
Sim
Sim
Sim
Sim
Sim
Sim
Sim
Sim
Where Fugu Mini beat Claude Opus 5.5
The tasks where I gave Fugu Mini a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Arcade
Game
Fugu Mini 8.5
·
Claude Opus 5.5 6.0
(+2.5)
What I saw: 55KB Breakout-style — paddle, ball, brick wall, particles, score HUD. Smoke-test PASS (large pixel diff after input).
Doom
Game
Fugu Mini 8.0
·
Claude Opus 5.5 5.8
(+2.2)
What I saw: Doom-style raycaster FPS with sprite enemies. Smoke-test PASS (pixel change after click+keys).
Dragonflight
Game
Fugu Mini 8.0
·
Claude Opus 5.5 6.0
(+2.0)
What I saw: Dragon flight through neon rings with HUD. Smoke-test PASS.
Skyrim
Game
Fugu Mini 8.0
·
Claude Opus 5.5 6.2
(+1.8)
What I saw: Mini gap-fill — 13KB Skyrim-style open world. Smoke-test PASS (0.9% diff).
Terrain
Visual
Fugu Mini 8.5
·
Claude Opus 5.5 6.8
(+1.7)
What I saw: Mini gap-fill (round 2) — Tron procedural terrain. Smoke-test PASS (8.6% diff — strong motion).
Where Claude Opus 5.5 beat Fugu Mini
The tasks where I gave Claude Opus 5.5 a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Webos
Page
Claude Opus 5.5 8.7
·
Fugu Mini 6.5
(+2.2)
What I saw: Polished NovaOS desktop: working Paint, Notes with a sidebar and autosave, a Terminal with neofetch/ls, a menu bar with a live clock and CPU, a side launcher and a dock with running dots, all in one cohesive macOS-like style. Very strong, but not clearly above the field's 9.0 best.
Aurora
Visual
Claude Opus 5.5 8.4
·
Fugu Mini 6.5
(+1.9)
What I saw: Lovely low-poly valley: layered shader aurora curtains, snowy peaks, a glowing cabin and a mirror lake reflection, plus palette and substorm controls. The foreground snow is a flat, overexposed cyan band that eats the bottom third of the frame.
Dogfight
Game
Claude Opus 5.5 7.8
·
Fugu Mini 6.0
(+1.8)
What I saw: Bright, well-lit low-poly world (lakes, forests, village, runway) with a decent jet model and a clean hull/boost/throttle HUD plus radar. The frame reads more like a flight sim than a fight: enemies are specks, the score is 0, and there is an odd flat orange disc in the scene.
Fractal
Sim
Claude Opus 5.5 8.0
·
Fugu Mini 6.5
(+1.5)
What I saw: Rich Mandelbrot deep zoom with an auto-tour, palette cycling, a live Julia-at-cursor preview and a tidy coordinate HUD. A hard straight-edged black band cuts across the right third of the frame, which looks like an interior/render artifact.
Galaxy
Sim
Claude Opus 5.5 8.0
·
Fugu Mini 6.5
(+1.5)
What I saw: 90k-star spiral with a glowing core, dust lanes, a mouse vortex, palettes and a clean HUD. It looks gorgeous overall. Visible vertical streak artifacts at the core (particles pulled into columns) mar the centrepiece.
Strengths & weaknesses I logged
Fugu Mini
Strengths
- Zero panel orchestration — much lower latency than Ultra
- Same Sakana subscription, no extra cost
- Doesn't time out on heavy game/3D prompts where Ultra stalls
Trade-offs
- Single model only — no ensemble verdict
- Newer than Ultra — less calibration / verification
Claude Opus 5.5
Strengths
- Frontier-class coding + agentic reasoning (Claude 5 family)
- 1M-token context — reads an entire codebase in one call
- All 50 one-shot builds rendered with zero console errors; all 23 games passed the input playtest
Trade-offs
- Premium pricing ($4/$20 per M) — route the everyday 90% to cheaper lanes
- One-shot builds can still ship logic bugs (e.g. a doom kill counter that miscounts)
Pricing & context — the spec sheet
| Spec | Fugu Mini | Claude Opus 5.5 |
|---|---|---|
| Vendor | Sakana AI | Anthropic |
| Context window | Single-model variant of Sakana's Fugu — no panel orchestration. Same API endpoint, much faster per call. | 1,000,000 tokens |
| Price | Same Sakana subscription pool as Fugu Ultra | $4 / $20 per M |
| Pricing detail | The non-Ultra `fugu` model on Sakana's API. Sakana describes it as 'Fast mini model optimized for low latency yet high quality responses.' Crucially: zero orchestration tokens per call (vs Ultra's panel of thousands). Returns in ~3 min instead of 6-15 min and doesn't time out on heavy prompts. | Anthropic's Opus 5.5 — 1M-token context, listed at $4 input / $20 output per million tokens. Benched through a Claude subscription; game tasks use our skill-infused AAA build prompts. |
| Release | 2026-06-15 | 2026-09 |
| Bench coverage | 36/37 scored · avg 7.75/10 | 50/50 scored · avg 7.57/10 |
The verdict — which should you pick?
Across 36 scored shared tasks, the averages are essentially tied — Fugu Mini 7.75 vs Claude Opus 5.5 7.75. This isn't the comparison where one wins; it's the comparison where you pick based on context, pricing, and what you're actually trying to ship.
If you only run one of these inside your stack, the head-to-head average above is the call. If you can run both, my honest play is to wire Fugu Mini and Claude Opus 5.5 both into the Agent Operating System and dispatch each from the kanban by task type — agent loops where latency matters more than panel consensus → Fugu Mini, hardest agentic builds → Claude Opus 5.5. That's the same setup I run for the 4,000+ founders inside the AI Profit Boardroom.
FAQ — Fugu Mini vs Claude Opus 5.5
Which is better, Fugu Mini or Claude Opus 5.5?
On Goldie Bench, Fugu Mini averages 7.75/10 across the shared tasks, with 2 gold, 0 silver, 0 bronze overall. Claude Opus 5.5 averages 7.75/10, with 0 gold, 0 silver, 1 bronze. Claude Opus 5.5 wins the head-to-head 18–17.
How much does Fugu Mini cost vs Claude Opus 5.5?
Fugu Mini: The non-Ultra `fugu` model on Sakana's API. Sakana describes it as 'Fast mini model optimized for low latency yet high quality responses.' Crucially: zero orchestration tokens per call (vs Ultra's panel of thousands). Returns in ~3 min instead of 6-15 min and doesn't time out on heavy prompts. Claude Opus 5.5: Anthropic's Opus 5.5 — 1M-token context, listed at $4 input / $20 output per million tokens. Benched through a Claude subscription; game tasks use our skill-infused AAA build prompts.
What's the context window for Fugu Mini vs Claude Opus 5.5?
Fugu Mini has a Single-model variant of Sakana's Fugu — no panel orchestration. Same API endpoint, much faster per call. context window. Claude Opus 5.5 has a 1,000,000 tokens context window.
When should I pick Fugu Mini over Claude Opus 5.5?
Pick Fugu Mini for: Agent loops where latency matters more than panel consensus; Quick first-drafts you'll refine downstream; Filling out a bench when Ultra is timing out. The trade-off is the weaknesses we logged on the bench: Single model only — no ensemble verdict; Newer than Ultra — less calibration / verification.
When should I pick Claude Opus 5.5 over Fugu Mini?
Pick Claude Opus 5.5 for: Hardest agentic builds; Whole-repo reasoning; Frontier one-shots. The trade-off is the weaknesses we logged on the bench: Premium pricing ($4/$20 per M) — route the everyday 90% to cheaper lanes; One-shot builds can still ship logic bugs (e.g. a doom kill counter that miscounts).
How does Goldie Bench score Fugu Mini vs Claude Opus 5.5?
Every demo on this page was built by Julian Goldie inside the Agent Operating System — same fixed prompt for both models, one shot, single HTML file out. Each result gets a 0–10 score on whether it ran, how close it hit the brief, and how good it looked. The highest score on each task gets gold; second gets silver; third gets bronze. See methodology for full provenance.
Related comparisons
Other head-to-heads using the same scoring system:
Fugu Mini vs Fusion Claude Opus 5.5 vs Fusion Fugu Mini vs Claude Opus 5 Claude Opus 5.5 vs Claude Opus 5 Fugu Mini vs Hermes MoA Claude Opus 5.5 vs Hermes MoA Fugu Mini vs GPT-5.6 Sol Claude Opus 5.5 vs GPT-5.6 SolFull model pages: Fugu Mini · Claude Opus 5.5 · back to the leaderboard
The same stack Julian uses
Run this stack yourself.
Every demo on this bench was built inside the Agent Operating System — one prompt, one shot, single HTML file out. The Agent OS, the prompts, the templates, the weekly walkthroughs and 4,000+ founders shipping with it every day all live inside the AI Profit Boardroom.
4,000+founders
258documented wins
38countries
$59/momonthly