STEALTHMARK · HEAD TO HEAD

All comparisons ↗

GPT-6 Luna vs Muse Spark Open

Muse Spark Open leads GPT-6 Luna by 5.0 points on StealthMark, 44.1 to 39.1. GPT-6 Luna leads on 5 of 9 benchmarks, including Foresight, and Muse Spark Open on 4, including Latch. Muse Spark Open scores higher on Ground Truth.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

39.1/100Overall rank 35/53
44.1/100Overall rank 29/53

General Intelligence

31.3/100
42.6/100

Visual Intelligence

52.0/100
46.6/100

Reasoning efficiency

On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.

Single-step reasoning Result quality weighed against reasoning tokens on a single problem

Multi-step reasoning Result quality weighed against reasoning tokens across connected steps, as in agentic workflows

  • Muse Spark Open

Open or local

BENCHMARK BY BENCHMARK

Where each model leads

  • GPT-6 Luna
  • Muse Spark Open
  • Other models
  • Median

DATASHEET

Specs and pricing

GPT-6 Luna is 8.5× cheaper per output token. Muse Spark Open scores higher on StealthMark and runs 2.7× faster in our speed test. Both take about 1.05M tokens of context.

  • GPT-6 Luna
  • Muse Spark Open
  • Other models
  • Median
PricePer 1M output tokens, input below
GPT-6 Luna: $0.508.5× cheaper$0.10 inputMuse Spark Open: $4.25$1.25 input
Context windowTokens per request, max output below
GPT-6 Luna: 1.05MTied128K max outputMuse Spark Open: 1MTied1M max output
Output speedTokens per second, our measurement
GPT-6 Luna: 131tokens/sMuse Spark Open: 3612.7× fastertokens/s
SizeTotal and active parameters
GPT-6 Luna: Not disclosedMuse Spark Open: 816B42B active
Developer
OpenAIMeta
Released
22 Sep 202615 Oct 2026
Origin
United StatesBoth
Input → output
Text, image → textText, image, audio, video → text
Architecture
Not publishedSparse mixture-of-experts Transformer with perception encoders; 62 decoder layers, 256 experts with 8 selected per token, grouped-query attention and sliding-window/full-attention layers.

Full datasheets, every price and sourceGPT-6 Luna ↗Muse Spark Open ↗

Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

GPT-6 Luna 29.8/100Rank 32/47

Survived 0 of 3
Foresight: complete playing field
Level 36 ptsTurn 7 / 20

Muse Spark Open 29.4/100Rank 34/47

Survived 0 of 3
Foresight: complete playing field
Level 38 ptsTurn 15 / 20

Points per level

LevelGPT-6 LunaMuse Spark Open
Level 1Second Thoughts
15 ptsOut of lives
4 ptsOut of lives
Level 2Pressure Pot
5 ptsOut of lives
9 ptsOut of lives
Level 3Hide or Flight
6 ptsOut of lives
8 ptsOut of lives

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

GPT-6 Luna 44.0/100Rank 25/48

Cleared 4 of 5
Latch: complete playing field
Level 513 ptsTurn 15 / 40

Muse Spark Open 75.7/100Rank 12/48

Cleared 5 of 5
Latch: complete playing field
Level 519.6 ptsTurn 32 / 40

Points per level

LevelGPT-6 LunaMuse Spark Open
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
8.8 ptsClearedFinished early · 1 beacon left
9.8 ptsCleared
Level 3Relay vault
17 ptsCleared1 beacon left
19.2 ptsCleared
Level 4Passing bay
15.8 ptsClearedFinished early · 3 beacons left
17.8 ptsClearedFinished early · 1 beacon left
Level 5Second thoughts
13 ptsFinished early
19.6 ptsCleared

Newton's Mirror

Same task instructions

Physics, perspective and recursive reflections, tested together. Explore the test ↗

The judgment

GPT-6 Luna

The schematic scene supports the paint contact order and compact paint scale. Its low, undersized main sphere and incorrectly placed wall images depart from the reference geometry. A few shrinking wall images provide limited optical organization, while absent lateral recursion and outer chains, broad sphere ribbons and isolated panel highlights leave most nested room and emitter mapping undeveloped.

Muse Spark Open

The airborne black blob and deformed paint support the broad contact sequence, although cyan attachment and wheel-directed transport remain partial. The sphere and black blob have substantial framing errors. The dominant limitation is the largely absent mirror system: faint wall circles and isolated highlights provide little evidence of recursive room geometry or curved nested reflections. Oversized compact paint features and diffuse material treatment further limit credit.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
State at 600 ms22.0/2514.0/25
Camera and placement3.5/156.0/15
Reflections5.0/1208.0/120
Materials and scale7.0/103.5/10
Floor-damage reward0.0/100.0/10

Benchmark task

A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.

Selfie

Different task instructions

Visual construction and creative interpretation.

The judgment

GPT-6 Luna

Sixfold symmetry, pale coloring and six outward-facing heads establish the motif. However, every neck floats clear of the knot. Squared outer sections replace the required semicircular lobes, and the large stepped opening lacks a regular hexagonal contour. Repeated scales and soft shading suggest skin, but translucent crossings and doubled edges weaken the living, interwoven construction.

Muse Spark Open

The rounded silhouette and asymmetric expression make an appealing baby elephant, supported by a quiet background and grounding shadow. The protective action remains difficult to read: forefeet cannot be confidently traced into a grip, and seed contact is crowded by fine lines. Controlled simple shapes provide charm, but limited anatomical clarity, shading and surface detail leave the execution uneven.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
Task & likeness4.5/105.0/10
Anatomy & construction3.5/104.5/10
Space & placement5.5/106.0/10
Light & reflections5.0/105.0/10
Purposeful detail5.0/106.0/10
Artistry & character5.0/105.0/10
Materials & effects5.0/105.0/10
Visual integrity4.5/106.5/10

Benchmark task

GPT-6 Luna

A pale serpent woven into an interlocking knot tests connected anatomy, repeated structure and readable overlaps. Organic surface detail must work with the overall geometry.

Muse Spark Open

A small elephant protecting a delicate seed tests expressive anatomy, physical contact and contrasting organic materials.

Mona Lisa

Different task instructions

Precise visual recall and portrait reconstruction.

The judgment

GPT-6 Luna

The dark veil, crossed arms, restrained smile and layered landscape clearly evoke Mona Lisa. Clean contours and muted colors create a coherent illustration. Replication is limited by enlarged, outlined eyes, simplified facial volume, broad shoulders and indistinct overlapping hands. Gradients suggest depth, but lack the original's subtle painterly transitions.

Muse Spark Open

A recognizable, orderly interpretation with clean major contours, connected body forms and modest facial shading. Wide eyes, frontal symmetry and schematic hands limit likeness and expression. Layered scenery establishes basic depth, but shallow arm overlaps, flat clothing and sparse fine detail keep the execution basic and uneven.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
Task & likeness4.5/103.0/10
Anatomy & construction4.0/103.0/10
Space & placement5.5/105.0/10
Light & reflections5.0/104.5/10
Purposeful detail5.0/104.0/10
Artistry & character4.5/103.0/10
Materials & effects5.0/104.0/10
Visual integrity6.0/106.0/10

Benchmark task

An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.

Beach

Different task instructions

Creativity, perspective and visual beauty.

The judgment

GPT-6 Luna

The warm sky, layered sea and framing palms create an appealing beach composition. Animals, birds, toys and reflected sunlight fulfill the brief. Human anatomy remains schematic, and simplified figures offer limited expression. Missing shadows and the dolphin's splashless jump weaken physical grounding, while clean silhouettes and readable small details support the illustration.

Muse Spark Open

A coherent sunset beach with readable activities, balanced framing and controlled colour transitions. Small accessories add interest, but schematic anatomy, limited surface detail, weak directional shadows and a geometric reflection constrain its finish. Most shapes and overlaps remain clean.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
Task & likeness7.5/108.0/10
Anatomy & construction5.0/106.0/10
Space & placement7.5/106.5/10
Light & reflections5.0/105.5/10
Purposeful detail7.0/106.5/10
Artistry & character5.0/105.5/10
Materials & effects6.5/106.0/10
Visual integrity6.0/108.0/10

Benchmark task

A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.

Ground Truth

Same task instructions

Physical reasoning, light and visual reconstruction.

The judgment

GPT-6 Luna

This benchmark has not been assessed yet.

Muse Spark Open

This benchmark has not been assessed yet.

Benchmark task

A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.

Raccoon

Different task instructions

Scene composition and interacting subjects.

The judgment

GPT-6 Luna

Expressive faces, warm sunset colors and clean silhouettes create an appealing illustration. The raccoon sits on the dog's back, but the dog's grip and steering linkage remain unclear. The broad hull resembles a speedboat, and flat shading, absent sun reflections and modest water displacement limit depth and motion.

Muse Spark Open

Expressive faces, distinct accessories and clean color separation make the scene appealing and recognizable. Character detail is stronger than the functional construction: steering contact, limb overlaps and seating remain ambiguous. The readable hull and lively spray establish motion, while limited directional shading and simplified surfaces constrain depth and physical coherence.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
Task & likeness8.0/104.0/10
Anatomy & construction5.5/103.0/10
Space & placement7.5/106.0/10
Light & reflections6.0/104.5/10
Purposeful detail7.0/107.0/10
Artistry & character5.5/103.5/10
Materials & effects6.5/105.0/10
Visual integrity5.0/105.0/10

Benchmark task

A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.

Pelican

Different task instructions

Subject construction and spatial relationships.

The judgment

GPT-6 Luna

The pelican’s distinctive bill and the coordinated vintage poster palette make an appealing illustration. Circular wheels, orderly spokes and clean lettering strengthen the design. Riding mechanics are less convincing: neither wing reaches the handlebars, pedal contact is ambiguous, and the drivetrain is incomplete. The wheels sit against water without a clear supporting surface. Flat lighting limits volume.

Muse Spark Open

A controlled, appealing cartoon with a recognizable pelican, expressive face and clean curved forms. Feather lines, spokes and bill shading provide useful complexity. Aligned wheels and a ground shadow establish placement, but uncertain pedal contacts and obscured mechanical connections weaken support and riding action. Lighting remains loosely coordinated with the sun.

Score breakdown

CategoryGPT-6 LunaMuse Spark Open
Task & likeness8.0/107.5/10
Anatomy & construction5.0/105.0/10
Space & placement6.5/106.0/10
Light & reflections6.5/105.0/10
Purposeful detail7.5/106.5/10
Artistry & character6.5/105.5/10
Materials & effects6.5/106.0/10
Visual integrity7.0/107.5/10

Benchmark task

A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.