Acc. XXV · Solitaria fugax — single-agent evaluation build, cultivated 2026

Sasuke vs Itachi — single-agent browser fight prototype

Systems R&D engineer · Agent evaluation · 2026 · Independent studio

A browser one-on-one fight prototype built end to end by a single agent in a single session with no harness, no gates, and no orchestration — the control case against the orchestrated, gated builds elsewhere in this catalogue.

Solitaria fugax — single-agent evaluation build, cultivated 2026

Field notes

The context

Every other entry in this catalogue runs through structured agent workflows — harnesses, verification gates, orchestration. The studio needed a control case: what does a capable but ungoverned single agent produce on the same class of problem, given one session and no scaffolding around it?

Cultivation

What I built

Commissioned and ran the evaluation: a browser one-on-one fight prototype built entirely by Sakana AI Fugu in a single agent session.
Deliberately withheld harness, verification gates, and orchestration scaffolding to isolate the agent's unassisted output.
Reviewed the resulting build against the orchestrated, gated projects elsewhere in the lab to characterise the difference.

Root system

How it works

A single agent, single session, browser-based build with no external harness or gate structure — the deliberate absence of architecture is the point of the evaluation.

Harvest

Outcomes

Produced a working comparison point: what a different agent product does with an interactive-systems brief absent any orchestration.
This is a throwaway evaluation prototype — no live deployment, no ongoing development.
The working repository is not currently available for inspection.

Herbarium

The work itself

In-match capture from a browser fight prototype, 1600 by 1000, rendered as a dark top-down low-poly night scene over rolling dark-green grass. Left of centre sits a large elliptical stone dais painted with concentric rings — a near-black outer disc, a dusky red ring, and a dark inner circle — reading as a stylised Uchiha crest. Slim black torch poles with pale lit tips ring the arena, each dropping a soft yellow pool of light onto the grass; low-poly rock clusters in pale lavender and dark red are scattered across the terrain. Below and right of the dais, a small dark-blue figure (Sasuke) stands beside a pale angular rock, and just above him a dark orange orb ringed with fire trails a short curving string of four ember dots up and to the right. To the right of the dais a second figure in black with red trim (Itachi) stands next to a rock outcrop with a bright pale-orange orb glowing at his feet, mid-impact. A dark beam and a red post at the lower-left edge are part of a torii gate cropped by the frame. The heads-up display overlays the scene: "SASUKE" in pale blue at top left above three stacked bars — an emptied dark health bar, a blue chakra bar filled to roughly two-thirds, and a full yellow stamina bar; "ITACHI · 2" in red at top right above a completely full green health bar, a blue chakra bar filled about a third, and a full yellow stamina bar; a small rounded "P2P" pill centred at the very top. Along the bottom centre sits a nine-slot ability bar of dark rounded tiles, each with an orange key label over a white name: LMB Taijutsu, X Jutsu, RMB Kunai with the count 14, Q Shuriken with the count 18, E Smoke with the count 3, F Fireball, R Charge, C Side-Step, and SPC Block. — Fig. 1A Katon fireball in flight with a second orb impacting on the opponent — the single capture that shows the prototype's whole loop at once: WebGL low-poly arena, dual-fighter health/chakra/stamina HUD, round score, P2P session pill, and a nine-ability bar with live ammo counters.

In-match capture from a browser fight prototype, 1600 by 1000, showing a dark low-poly night arena from a fixed top-down camera. The elliptical crest dais — black outer disc, dusky red ring, dark centre — sits at upper centre, and directly beneath its lower edge a fireball is detonating: a spreading cloud of roughly two dozen glowing orange ember blobs at varying sizes, brightest at the core, throwing warm light up onto the underside of the dais and across the grass. To the left of the blast a small blue-clad figure (Sasuke) stands against a pale angular rock; to the lower right of it a black figure with red trim (Itachi) stands clear of the embers, both caught inside the same exchange. Black torch poles with lit pale tips ring the arena, each casting a yellow pool. In the lower centre foreground a dark red torii gate stands with a heavy black crossbeam, laying a long shadow down the grass, and clusters of faceted teal-and-brown low-poly pine trees crowd the bottom edge and lower-left corner. HUD overlay: "SASUKE" in pale blue at top left above a green health bar filled to about forty per cent, a blue chakra bar at roughly a fifth, and a full yellow stamina bar; "ITACHI" in red at top right with no round number beside it, above a full green health bar, a blue chakra bar at about a fifth, and a full yellow stamina bar; a rounded "P2P" pill centred at the top. The nine-slot ability bar runs along the bottom centre: LMB Taijutsu, X Jutsu, RMB Kunai 14, Q Shuriken 19, E Smoke 3, F Fireball, R Charge, C Side-Step, SPC Block. — Fig. 2The fireball's detonation frame, caught mid-particle-burst with both fighters in the blast radius — additive ember particles and the light they throw onto the dais and terrain are the prototype's main VFX read.

In-match capture from a browser fight prototype, 1600 by 1000, in a dark top-down low-poly night arena over dark-green grass. The elliptical crest dais with its black outer disc, dusky red ring and dark centre sits at centre-left. Just below the dais's lower-right edge, a vivid magenta-pink energy burst erupts around a small dark figure (Sasuke): flame-shaped tendrils of hot pink flare upward and outward from him with a few small yellow-white sparks at the base, and the glow spills onto the grass and onto a pale angular rock immediately to his left. Above and right of the dais stands Itachi, a small black silhouette with two glowing red pinpoint eyes. Slim black torch poles with pale lit tips ring the arena, each casting a yellow light pool; lavender-and-red low-poly rocks are scattered around. At the top edge of the frame the dark red uprights and black crossbeam of a torii gate are cropped by the border, with a couple of faceted teal pine trees beside them. HUD overlay: "SASUKE" in pale blue at top left above a green health bar reduced to a short sliver at the far left, a blue chakra bar filled to about half, and a full yellow stamina bar; "ITACHI · 1" in red at top right above a full green health bar, a blue chakra bar at roughly a third, and a full yellow stamina bar; a rounded "P2P" pill centred at the top. The bottom-centre ability bar shows nine dark tiles: LMB Taijutsu, X Jutsu, RMB Kunai 14, Q Shuriken 19, E Smoke 3, F Fireball, R Charge, C Side-Step, SPC Block. — Fig. 3The signature jutsu firing on a near-dead health bar — a second, colour-separated particle system (magenta tendrils plus sparks) proving the prototype ships more than one distinct ability VFX.

In-match capture from a browser fight prototype, 1600 by 1000, framed top-down on the arena's elliptical crest dais: a near-black outer disc, a dusky red ring, and a dark inner circle. A bright pale-orange fireball orb sits on the red ring at the dais's lower right, trailing a curving line of five shrinking ember dots up and to the left then right toward Itachi, who stands as a small black silhouette with two glowing red eyes on the dais's upper edge; the orb casts a red-orange wash across the ring beneath it. On the far left of the frame a previous impact is still dissipating — a scatter of a dozen orange ember blobs around a black scorch smear on the grass. Below the dais, a small dark-blue figure (Sasuke) stands on the grass ahead of a large pale-lavender-and-red low-poly rock cluster. Black torch poles with lit pale tips ring the arena and drop yellow light pools; more rock clusters sit to the right. At the top edge, the dark red uprights and heavy black crossbeam of a torii gate are cropped by the frame, with a faceted teal pine tree beside them. HUD overlay: "SASUKE" in pale blue at top left above a green health bar filled to a little over half, a blue chakra bar at about forty per cent, and a full yellow stamina bar; "ITACHI · 1" in red at top right above a full green health bar, a blue chakra bar at roughly two-thirds, and a full yellow stamina bar; a rounded "P2P" pill centred at the top. The nine-slot bottom ability bar reads LMB Taijutsu, X Jutsu, RMB Kunai 14, Q Shuriken 19, E Smoke 3, F Fireball, R Charge, C Side-Step, SPC Block. — Fig. 4A projectile tracking across the crest dais toward the opponent while the previous impact's embers still fade at the left — the frame that shows travel, aim and residual state coexisting in one tick of the game loop.

Pressed leaf — what it taught

An orchestrated, gated workflow's value is easiest to see in contrast — this single-session, ungoverned build is what the harness and verification gates elsewhere in the studio's projects are measured against.