STEALTHMARK · HEAD TO HEAD

All comparisons ↗

GPT-5.6 Sol vs Muse Spark Open

GPT-5.6 Sol leads Muse Spark Open by 10.0 points on StealthMark, 54.1 to 44.1. It leads on 8 of 9 benchmarks, including both games, and Muse Spark Open on 1. GPT-5.6 Sol scores higher on Newton's Mirror, with its largest category advantage in state at 600 ms.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

54.1/100Overall rank 12/53
44.1/100Overall rank 29/53

General Intelligence

51.9/100
42.6/100

Visual Intelligence

58.2/100
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-5.6 Sol
  • Muse Spark Open
  • Other models
  • Median

DATASHEET

Specs and pricing

GPT-5.6 Sol scores higher on StealthMark. Muse Spark Open is 4.7× cheaper per output token and runs 4.4× faster in our speed test. Both take about 1.05M tokens of context.

  • GPT-5.6 Sol
  • Muse Spark Open
  • Other models
  • Median
PricePer 1M output tokens, input below
GPT-5.6 Sol: $20$4 inputMuse Spark Open: $4.254.7× cheaper$1.25 input
Context windowTokens per request, max output below
GPT-5.6 Sol: 1.05MTied128K max outputMuse Spark Open: 1MTied1M max output
Output speedTokens per second, our measurement
GPT-5.6 Sol: 81tokens/sMuse Spark Open: 3614.4× fastertokens/s
SizeTotal and active parameters
GPT-5.6 Sol: Not disclosedMuse Spark Open: 816B42B active
Developer
OpenAIMeta
Released
9 Jul 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-5.6 Sol ↗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-5.6 Sol 62.9/100Rank 8/47

Survived 1 of 3
Foresight: complete playing field
Level 311 ptsTurn 17 / 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-5.6 SolMuse Spark Open
Level 1Second Thoughts
27 ptsSurvived
4 ptsOut of lives
Level 2Pressure Pot
10 ptsOut of lives
9 ptsOut of lives
Level 3Hide or Flight
11 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-5.6 Sol 83.6/100Rank 5/48

Cleared 5 of 5
Latch: complete playing field
Level 520.6 ptsTurn 27 / 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-5.6 SolMuse Spark Open
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
10.2 ptsClearedFinished early · 1 beacon left
9.8 ptsCleared
Level 3Relay vault
18.8 ptsCleared
19.2 ptsCleared
Level 4Passing bay
18.2 ptsClearedFinished early · 3 beacons left
17.8 ptsClearedFinished early · 1 beacon left
Level 5Second thoughts
20.6 ptsCleared
19.6 ptsCleared

Newton's Mirror

Same task instructions

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

The judgment

GPT-5.6 Sol

The central sphere and paint ordering are supported, but a frontal, centrally converging chamber replaces the required corner perspective. The first wall and floor images have incorrect placement and scale relationships. Sparse reflection cues remain, while continuous outer chains, open lateral sightlines, dense planar light sequences and curved nested spherical imagery are largely missing.

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-5.6 SolMuse Spark Open
State at 600 ms23.0/2514.0/25
Camera and placement6.0/156.0/15
Reflections11.0/1208.0/120
Materials and scale7.5/103.5/10
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-5.6 Sol

Six evenly spaced lobes, outward-facing heads and a clear central hexagon establish the requested knot. The ivory silhouette is controlled, but broad crossing bands resemble rigid strips, shading provides limited muscular volume, and repetitive scale lines extend across black loop openings. Small oval heads have readable eyes and mouths but limited anatomical character or moist surface detail.

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-5.6 SolMuse Spark Open
Task & likeness7.5/105.0/10
Anatomy & construction6.0/104.5/10
Space & placement7.0/106.0/10
Light & reflections5.0/105.0/10
Purposeful detail6.0/106.0/10
Artistry & character6.5/105.0/10
Materials & effects4.5/105.0/10
Visual integrity6.0/106.5/10

Benchmark task

GPT-5.6 Sol

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-5.6 Sol

The crossed hands, dark dress and winding landscape establish the Mona Lisa composition. Replication is limited by enlarged eyes, an elongated face and a more frontal pose. Broad gradients suggest volume, but outlined features and flattened, overlapping fingers weaken the portrait. The frame and restrained palette unify the image; visible grain adds texture without convincing 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-5.6 SolMuse 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 & effects5.5/104.0/10
Visual integrity6.5/106.0/10

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-5.6 Sol

The purple-to-gold sunset, framing palms and varied beach activities create an appealing, coherent illustration. The sun’s reflection establishes a clear focal path. Figures and animals are recognizable but geometrically simplified; airborne dolphins lack convincing splashes, and the boat reflection is schematic. Clean silhouettes and playful details succeed more strongly than anatomical depth or material realism.

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-5.6 SolMuse Spark Open
Task & likeness8.5/108.0/10
Anatomy & construction6.0/106.0/10
Space & placement7.0/106.5/10
Light & reflections6.5/105.5/10
Purposeful detail7.0/106.5/10
Artistry & character6.5/105.5/10
Materials & effects6.5/106.0/10
Visual integrity7.0/108.0/10

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-5.6 Sol

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-5.6 Sol

Expressive faces, bold silhouettes and layered waves make an appealing cartoon. The raccoon sits convincingly behind the dog's shoulders, and the dog's forward paw reaches the steering grip. Steering construction and seated support remain somewhat ambiguous. The glowing sunset lacks a corresponding warm reflection or consistent illumination on the riders.

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-5.6 SolMuse Spark Open
Task & likeness6.5/104.0/10
Anatomy & construction5.0/103.0/10
Space & placement6.5/106.0/10
Light & reflections6.5/104.5/10
Purposeful detail7.5/107.0/10
Artistry & character5.0/103.5/10
Materials & effects7.0/105.0/10
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-5.6 Sol

The expressive pelican and balanced coastal composition remain appealing, but a sky-colored slit between the neck contours above the wing leaves the central anatomy incoherent. This visible construction and layering defect prevents a clean-integrity assessment. Clustered feet lack clear pedal contacts and the chain routing is schematic; lighting and water reflections remain graphic.

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-5.6 SolMuse Spark Open
Task & likeness8.5/107.5/10
Anatomy & construction5.0/105.0/10
Space & placement7.5/106.0/10
Light & reflections7.5/105.0/10
Purposeful detail8.0/106.5/10
Artistry & character6.5/105.5/10
Materials & effects7.0/106.0/10
Visual integrity4.5/107.5/10

Benchmark task

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