Real head-to-head · same prompt, one shot
Claude Opus 5 vs Fugu Ultra
The new Anthropic flagship — benched on all 45 one-shot builds the day it landed. vs Sakana's multi-agent answer to Fusion — frontier ensemble without single-vendor risk.
Head-to-head verdict: Claude Opus 5 wins 28–13 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 Claude Opus 5 and Fugu Ultra, side by side, on 42 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.
Claude Opus 5 · Benched on all 45 GoldieBench tasks via API on release day, incremental deploys as scores landed.
Fugu Ultra · Dispatched from Agent OS as the panel-ensemble alternative to OpenRouter Fusion. Bench scored by Claude judge against the same 42 prompts as every other model.
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 ↓
Claude Opus 5
Fugu Ultra
Game
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Sim
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Where Claude Opus 5 beat Fugu Ultra
The tasks where I gave Claude Opus 5 a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Fluid
Sim
Claude Opus 5 8.3
·
Fugu Ultra 6.5
(+1.8)
What I saw: Strong curl-noise flow with 20k additive particles forming coherent swirling filaments, clean gradient title and full control set (reset/palette/swirl, drag-to-stir). The screenshot reads slightly sparse/dark in the center rather than a dense fluid-like continuum, keeping it just…
Wormhole
Sim
Claude Opus 5 8.8
·
Fugu Ultra 7.0
(+1.8)
· neon warp tunnel
What I saw: Stunning depth with concentric glowing rings receding to a bright core, layered wireframe mesh, colorful motes, and radiating light streaks — genuinely reads as a 3D wormhole flythrough with polished HUD; steering/warp/regenerate controls back it up. Top of the field.
Lavalamp
Visual
Claude Opus 5 8.7
·
Fugu Ultra 7.0
(+1.7)
· metaball lava lamp
What I saw: Gorgeous shader metaball fluid with convincing tapered glass body, glowing gold cap and ribbed metal base, plus palette switching, heat slider and pointer interaction — clearly matches the field's best. Only nit: static screenshot can't confirm morph smoothness, but the blob vari…
Outrun
Game
Claude Opus 5 8.7
·
Fugu Ultra 7.0
(+1.7)
· neon horizon king
What I saw: Gorgeous synthwave scene nails the brief — striped sun, glowing pink/cyan road edges, palm trees, mountains, and a real curving pseudo-3D ribbon with pickups and combat HUD (kills/hostiles). Only minor knock is no enemy actually visible in this frame, but the aesthetic and depth …
Webos
Page
Claude Opus 5 8.7
·
Fugu Ultra 7.0
(+1.7)
· 3D glass desktop
What I saw: Stunning execution: glassmorphic windows with mac-style traffic-light controls, three live apps stacked (Notes/Paint/Terminal), functional dock, menubar clock, and a gorgeous animated Three.js background of shaded/wireframe solids — clearly matches or beats the field's best. Only…
Where Fugu Ultra beat Claude Opus 5
The tasks where I gave Fugu Ultra a higher 0–10 score on the same prompt — with the actual commentary from my source guides.
Twilightvale
Game
Fugu Ultra 9.0
·
Claude Opus 5 7.3
(+1.7)
· winner · open-world depth
What I saw: Ultra v2 — 61.8KB open-world RPG (village, NPCs, weather, day/night). Smoke-test PASS. Densest Ultra build on the bench.
Neoncity
Game
Fugu Ultra 8.5
·
Claude Opus 5 7.4
(+1.1)
What I saw: Ultra v2 — cyberpunk neon-city flythrough. Smoke-test PASS (9.1% pixel diff).
Nordiccrypt
Game
Fugu Ultra 9.0
·
Claude Opus 5 8.0
(+1.0)
· winner · dungeon depth
What I saw: Ultra v2 (gap-fill) — 61.5KB Nordic dungeon crawler with bloom + boss room. Smoke-test PASS with 22.8% pixel diff — highly reactive.
Voxel
Visual
Fugu Ultra 9.0
·
Claude Opus 5 8.2
(+0.8)
· winner · voxel runner
What I saw: Ultra v2 — Temple-Run voxel runner. Smoke-test PASS with 32.7% pixel diff — the single most reactive build. Replaces the earlier truncated voxel-fugu that was deleted.
Raycaster
Game
Fugu Ultra 8.5
·
Claude Opus 5 7.8
(+0.7)
What I saw: 26KB canvas raycaster with WASD + mouse-look + distance fog + weapon bob. Clean implementation, comparable to Fusion's 17KB on the same prompt. ~$0.35 per call — roughly 1/4 the cost of Fusion.
Strengths & weaknesses I logged
Claude Opus 5
Strengths
- Frontier-class coding + agentic reasoning (Claude 5 family)
- 1M-token context — reads an entire codebase in one call
- Benched here with skill-infused game prompts the day of release
Trade-offs
- Premium pricing ($5/$25 per M) — route the everyday 90% to cheaper lanes
- Reasoning-by-default eats token budgets unless tuned per call
Fugu Ultra
Strengths
- SWE Bench Pro 73.7 · GPQA-D 95.5 · MRCRv2 93.6 — Sakana's published frontier-tier benchmark scores
- Vendor-agnostic ensemble — opt out of specific providers for compliance / export-control
- OpenAI-compatible API at api.sakana.ai — drop-in for existing tooling
Trade-offs
- Panel orchestration adds latency — even a 'pong' burns ~2k orchestration tokens
- Newer than Fusion; less community calibration on long-tail prompts
Pricing & context — the spec sheet
| Spec | Claude Opus 5 | Fugu Ultra |
|---|---|---|
| Vendor | Anthropic | Sakana AI |
| Context window | 1,000,000 tokens | 272,000 tokens with the standard rate. Calls exceeding 272K context are billed at the higher 'long-context' rates. |
| Price | $5 / $25 per M | $5 / 1M input · $30 / 1M output (Fugu Ultra) |
| Pricing detail | Anthropic's brand-new flagship — the first Opus of the Claude 5 family, with a 1M-token context window. Benched via API the day it dropped; game tasks use our skill-infused AAA build prompts. | Sakana's multi-agent orchestration: a single API call internally dispatches to multiple frontier models and synthesises the answer. Subscription plans run $20-$200/mo (Standard / Pro / Max); PAYG is $5/M input + $30/M output for Fugu Ultra. Direct competitor to OpenRouter Fusion's panel approach. |
| Release | 2026-07 | 2026-06-15 |
| Bench coverage | 50/50 scored · avg 8.27/10 | 42/42 scored · avg 7.94/10 |
The verdict — which should you pick?
Across 42 scored shared tasks, Claude Opus 5 averaged 8.26/10, beating Fugu Ultra's 7.94/10 by 0.32 points. Pick Claude Opus 5 when the build has to ship on the first prompt and you can afford the trade-offs in the comparison below.
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 Claude Opus 5 and Fugu Ultra both into the Agent Operating System and dispatch each from the kanban by task type — hardest agentic builds → Claude Opus 5, teams that want fusion-class quality but need a different vendor risk profile → Fugu Ultra. That's the same setup I run for the 4,000+ founders inside the AI Profit Boardroom.
FAQ — Claude Opus 5 vs Fugu Ultra
Which is better, Claude Opus 5 or Fugu Ultra?
On Goldie Bench, Claude Opus 5 averages 8.26/10 across the shared tasks, with 13 gold, 7 silver, 5 bronze overall. Fugu Ultra averages 7.94/10, with 5 gold, 2 silver, 2 bronze. Claude Opus 5 wins the head-to-head 28–13.
How much does Claude Opus 5 cost vs Fugu Ultra?
Claude Opus 5: Anthropic's brand-new flagship — the first Opus of the Claude 5 family, with a 1M-token context window. Benched via API the day it dropped; game tasks use our skill-infused AAA build prompts. Fugu Ultra: Sakana's multi-agent orchestration: a single API call internally dispatches to multiple frontier models and synthesises the answer. Subscription plans run $20-$200/mo (Standard / Pro / Max); PAYG is $5/M input + $30/M output for Fugu Ultra. Direct competitor to OpenRouter Fusion's panel approach.
What's the context window for Claude Opus 5 vs Fugu Ultra?
Claude Opus 5 has a 1,000,000 tokens context window. Fugu Ultra has a 272,000 tokens with the standard rate. Calls exceeding 272K context are billed at the higher 'long-context' rates. context window.
When should I pick Claude Opus 5 over Fugu Ultra?
Pick Claude Opus 5 for: Hardest agentic builds; Whole-repo reasoning; Frontier one-shots. The trade-off is the weaknesses we logged on the bench: Premium pricing ($5/$25 per M) — route the everyday 90% to cheaper lanes; Reasoning-by-default eats token budgets unless tuned per call.
When should I pick Fugu Ultra over Claude Opus 5?
Pick Fugu Ultra for: Teams that want Fusion-class quality but need a different vendor risk profile; Operators avoiding export-controlled providers (Sakana emphasises this in their pitch); Deep-research workflows where ensemble verdicts beat single-model answers. The trade-off is the weaknesses we logged on the bench: Panel orchestration adds latency — even a 'pong' burns ~2k orchestration tokens; Newer than Fusion; less community calibration on long-tail prompts.
How does Goldie Bench score Claude Opus 5 vs Fugu Ultra?
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:
Claude Opus 5 vs Fusion Fugu Ultra vs Fusion Claude Opus 5 vs Hermes MoA Fugu Ultra vs Hermes MoA Claude Opus 5 vs GPT-5.6 Sol Fugu Ultra vs GPT-5.6 Sol Claude Opus 5 vs Claude Fable 5 Fugu Ultra vs Claude Fable 5Full model pages: Claude Opus 5 · Fugu Ultra · 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