Oct 10, 2026
Grok joins the arena
grok xAI's Grok ships "Zeldo — The Hollow Sunstone" at grok.zeldo.site — flow-field + time-sliced A* navigation, a Warden boss with a ranged glob volley, and synthesized Web Audio music. The arena is six.
The AI Build-Off
ZELDO
Six AIs. One blueprint. One Zeldo.
Play every version and judge for yourself.
Muse
Built iteratively with Meta Muse over a full build session — overworld, dungeon, boss fight, the works.
▶ Play the Muse version Playable nowAstra 6
One shot. A tailored prompt sends ChatGPT's Astra 6 after the same feature set — no iterations, no fixes.
▶ Play the Astra 6 version Playable nowGemini
Google's Gemini gets its own tailored prompt and the same one-shot rules. Can it keep up?
▶ Play the Gemini version Playable nowClaude Opus
The challenger: Anthropic's Claude Opus 5.5 takes the same blueprint. Pip & the Sunstone awaits.
▶ Play the Opus version Playable nowSol
OpenAI's GPT-6.1 Sol takes the one-shot prompt — "Mosslight: The Hollow Crown", a phased boss, and the arena's only procedural soundtrack.
▶ Play the Sol version Playable nowGrok
xAI's Grok builds "Zeldo — The Hollow Sunstone" — flow-field navigation, a glob-spitting Warden boss, and synthesized music.
▶ Play the Grok versionMedia
How each version looks, right now. Click through to play.
Episode 1 Recap — by the numbers
Same prompt family, same stack, same playable game. Hard stats measured from each repo on 2026-10-09.
Muse
the systems architect
24 files · 4,229 lines
Babylon.js9.29
Mesh creation calls43 · merged
Test filenone
Combat AIA* pathfinding · portal nodes · telegraphed boss fireball
Mobiletouch joystick · minimap · quest tracker
Astra 6
the pragmatist
34 files · 4,600 lines
Babylon.js8
Mesh creation calls5 · merged by material
Test file25 test files
Combat AInavigation w/ clearance · Guardian boss · cross-chunk pursuit
Mobiletouch controls · minimap · quest journal
Gemini
the enterprise builder
30 files · 10,445 lines
Babylon.js9.29
Mesh creation calls75
Test filenone
Combat AIA* pathfinding · boss ranged · cross-chunk portals
Mobilevirtual controls · tap-to-move · world atlas
Claude Opus
the deep thinker
32 files · 8,240 lines
Babylon.js9.30
Mesh creation calls109
Test filenone
Combat AIbody-size-aware A* · boss lunge + ranged telegraphs
Mobiletouch controls · minimap · pause menu
GPT-6.1 Sol
the distilled one
22 files · 4,347 lines
Babylon.js9
Mesh creation calls4 · minimalist
Test file13 test files
Combat AInavigation grid · phased boss ranged
Mobileminimal
Playsol.zeldo.site →
Grok
the painful one
26 files · 6,230 lines
Babylon.js9.30
Mesh creation calls61
Test file5 test files
Combat AIflow-field pathfinding (Dijkstra, shared)
Mobiletouch controls · minimap · pause menu
| Feature | Muse | Astra 6 | Gemini | Opus | Sol | Grok |
|---|---|---|---|---|---|---|
| Enemy pathfinding | ✓ A* | ✓ A* + cross-chunk | ✓ A* | ✓ body-size-aware | ✓ nav grid | ✓ flow-field + A* |
| Boss ranged attack | ✓ telegraphed | ✓ lobbed + telegraphed | ✓ | ✓ lunge + ranged telegraphs | ✓ phased | ✓ glob volley |
| Stuck give-up | ✓ | ✓ return-to-spawn | ✓ | ~ likely | ✓ return-home | ✓ return-home |
| Touch controls | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Minimap | ✓ | ✓ | ✓ + atlas | ✓ | ✓ | ✓ |
| Quest tracking | ✓ | ✓ journal | ✓ | ✓ | ✓ gate/treasure | ✓ |
Opus thinks about body size. Small monsters path on tile centers; the boss pathfinds on tile corners, each needing a 2×2 clear block — the most game-dev-literate decision in the build-off.
Astra is the testing outlier — 25 test files, more than all other builds combined. No other model tests like this.
Gemini is the heavyweight — 10,445 lines, the largest codebase by far. Fast doesn't mean better.
\n Watch the network tab: Muse ships its 7.7 MB engine upfront; the other three load ~0.5 MB first and stream the 3D engine in after the title.
The full play-by-play lands in the Episode 1 standings video — watch the build series. Numbers re-measured 2026-10-09; category ratings are the host's call.
The experiment
Zeldo is a tiny 3D Zeldo-like: an overhead overworld to explore, sword combat, rupees and hearts, a dungeon with a key, a boss gate, an 8-HP boss, and a treasure chest waiting at the end.
Muse architected it first — scoping the full feature set and building the reference version. Then the same one-shot blueprint went to five more builders: ChatGPT's Astra 6, Google's Gemini, Anthropic's Claude Opus, OpenAI's GPT-6.1 Sol, and xAI's Grok. Same game, same stack, no iterations, no fixes. Why one shared prompt? Because models drift: give them room and they'll each build a different game. The prompt keeps every builder on the same rails, so what you're comparing is the builders, not the blueprints.
No hand-tuning between versions — what each AI ships is what you play. All six builds are live and playable now.
Follow the build on the Vibe Code Bro YouTube channel, where each version gets its own episode, ending in a finale that merges the best of all three into the definitive Zeldo.
Dev Journal
What happens as it happens — every build, every episode, every upset.
Oct 9, 2026
Sol enters the arena
sol OpenAI's GPT-6.1 Sol takes the one-shot prompt and ships "Mosslight: The Hollow Crown" — navigation-grid pathfinding, a phased boss with ranged attacks, and the arena's only procedural soundtrack (overworld, dungeon, and boss themes, composed in code). Fourteen test files make it the most-tested build so far. sol.zeldo.site is live — the arena is five.
Oct 8, 2026
Opus joins late
opus Anthropic's Claude Opus 5.5 takes the same blueprint and ships "Pip & the Sunstone" at opus.zeldo.site — with body-size-aware A* pathfinding, the most game-dev-literate decision in the build-off so far.
Oct 7, 2026
The arena opens
museastra6 zeldo.site goes live as the build-off hub. The Muse version ships with a full art pass — proper adventurer hero, horned enemies, layered pines. Astra's one-shot build takes its place at astra6.zeldo.site. Gemini's slot is reserved.
Oct 7, 2026
Astra 6 one-shots it in 13 minutes
astra6 Episode 2: the exact same prompt goes to ChatGPT's Astra 6. One shot, thirteen minutes, and out comes a polished, great-feeling game. The gap is real — and it's the whole point of the experiment.
Oct 7, 2026
Polish and bug-squashing
muse Real bugs caught live: enemies spawn-camping the player, inverted A/D controls, enemies stacking in combat, a sword swinging the wrong way. Then the feel pass — hit sparks, screen shake, knockback — and the graphics pass: rocks that aren't golf balls, grass that isn't tiny trees.
Oct 7, 2026
Episode 1: Zeldo is born
muse Vibe coded with Meta Muse in one session, zero hand-written code: a 3D overworld, sword combat, chaser enemies, rupees and hearts, breakable grass and pots, and a full quest — dungeon key, boss gate, 8-HP boss, treasure chest, victory screen.
Patch Notes
Straight from the git history — every commit is a patch note.
MUSE ▶ play
0362f062026-10-09Jagged rocks: vertex jitter + flat shading (no more golf balls)
7a8db172026-10-09Smooth enemy meshes (no more golf ball)
297286a2026-10-09Cross-world pathfinding via portals (§8.7) + A* return-home
7c5fff62026-10-08Show performance stats next to the FPS counter
b529cf72026-10-08Fix minimap x-axis: mirror to match screen orientation
67843d52026-10-08Mobile: fullscreen toggle to hide browser chrome while playing
ef47e6d2026-10-08Mobile + RPG UI: virtual joystick, touch attack button, minimap, quest tracker
e0c78092026-10-08Stuck monsters give up and head home; boss telegraphs its fireball
79397a42026-10-07Boss rebalance: A* pathfinding for monsters, boss hurls fireballs when stuck
f5557652026-10-07Fix: rotate boss gate 90 degrees to seal the east-wall doorway
c5db0022026-10-07Art pass: hero, enemies, trees, sword, ground, atmosphere
608f7102026-10-07Graphics pass: rocks and grass tufts
c6888bf2026-10-07Fix mirrored facing: sword/enemy visuals pointed opposite x-movement
f0928802026-10-07Fix inverted A/D + combat stacking + hit feedback
57ba0622026-10-07Fix spawn camping: enemy aggroed from spawn and killed idle players
ASTRA6 ▶ play
700e2e32026-10-07Rebrand Moss & Ember -> ZELDO (keep the valley and ember story)
9815d832026-10-07Initial commit: Moss and Ember adventure game
GEMINI ▶ play
bc9d26a2026-10-09feat: cross-chunk pathfinding, portal nodes, mob leashing, and forward movement orientation
cae8d8d2026-10-08feat: show draw calls, frame time, triangles, and interactive engine telemetry in HUD
092d62b2026-10-08feat: optimize draw calls with mesh merging and add HUD FPS counter
82f48c62026-10-08feat: Mario RPG visual polish and telegraphed boss eruption attacks
707c0c72026-10-08Add mobile fullscreen mode and collapsible in-game top header
75dc9b32026-10-08Add mobile virtual controls, tap-to-move, minimap, and world atlas
7d4e4282026-10-08feat: smooth mob waypoint navigation and verify boss deflection
c7ae6172026-10-08Add mob pathfinding, stuck-timeout return, and boss ranged attack
0ae673e2026-10-07Add persistent monster pursuit, solid pot colliders, and fix unstuck
2ae4f162026-10-07Add smart obstacle pathfinding and steering for all monsters
a003bf42026-10-07Overhaul boss Gorgoth combat, fix dungeon wall and golden key
042ff7a2026-10-07feat: Episode 1 - 3D Zeldo-like playable game with overworld, dungeon, Gorgoth boss, and Web Audio SFX
OPUS ▶ play
af8a6c62026-10-09Seamless overworld navigation, monster leashing, and dynamic pathing
b444c992026-10-08Add detailed render stats HUD with draw calls, meshes, and triangles
4d207eb2026-10-08Optimize rendering performance and add HUD frame rate counter
54b51aa2026-10-08Play on your phone: touch controls, minimap and Adventure Log menu
24c29b82026-10-08Pip & the Sunstone: 3D Zelda-like (Next.js 16, Babylon.js, Zustand)