STEALTHMARK · HEAD TO HEAD

All comparisons ↗

GPT-6.1 Terra Low vs Muse Spark Open

Muse Spark Open leads GPT-6.1 Terra Low by 2.8 points on StealthMark, 44.1 to 41.3. GPT-6.1 Terra Low and Muse Spark Open each lead on 4 of 9 benchmarks, with 1 tied. GPT-6.1 Terra Low leads Foresight and Muse Spark Open leads Latch. Muse Spark Open scores higher on Ground Truth.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

41.3/100Overall rank 35/55
44.1/100Overall rank 30/55

General Intelligence

34.3/100
42.6/100

Visual Intelligence

53.1/100
46.6/100

Open or local

BENCHMARK BY BENCHMARK

Where each model leads

  • GPT-6.1 Terra Low
  • Muse Spark Open
  • Other models
  • Median

DATASHEET

Specs and pricing

  • GPT-6.1 Terra Low
  • Muse Spark Open
  • Other models
  • Median
PricePer 1M output tokens, input below
GPT-6.1 Terra Low: No list priceMuse Spark Open: $4.25$1.25 input
Context windowTokens per request, max output below
GPT-6.1 Terra Low: Not publishedMuse Spark Open: 1M1M max output
Output speedTokens per second, our measurement
GPT-6.1 Terra Low: Not measuredMuse Spark Open: 361tokens/s
SizeTotal and active parameters
GPT-6.1 Terra Low: Not disclosedMuse Spark Open: 816B42B active
Developer
Not publishedMeta
Released
Not published15 Oct 2026
Origin
Not publishedUnited States
Input → output
Not publishedText, 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 sourceMuse 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-6.1 Terra Low 36.1/100Rank 26/51

Survived 1 of 3
Foresight: complete playing field
Level 39 ptsTurn 20 / 20

Muse Spark Open 29.4/100Rank 36/51

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

Points per level

LevelGPT-6.1 Terra LowMuse Spark Open
Level 1Second Thoughts
4 ptsOut of lives
4 ptsOut of lives
Level 2Pressure Pot
8 ptsOut of lives
9 ptsOut of lives
Level 3Hide or Flight
9 ptsSurvived
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-6.1 Terra Low 62.4/100Rank 23/52

Cleared 4 of 5
Latch: complete playing field
Level 520.6 ptsTurn 27 / 40

Muse Spark Open 75.7/100Rank 14/52

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

Points per level

LevelGPT-6.1 Terra LowMuse Spark Open
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.2 ptsCleared
9.8 ptsCleared
Level 3Relay vault
18.8 ptsCleared
19.2 ptsCleared
Level 4Passing bay
10.2 ptsFinished early
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-6.1 Terra Low

Deformed colored paint and a separate airborne black body establish readable interaction history. Cyan has travelled too far, framing differs substantially, and the mirror system supplies only elementary bands and oval copies. Missing recursive geometry, nested spherical imagery and emitter mapping remain the dominant weaknesses.

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-6.1 Terra LowMuse Spark Open
State at 600 ms22.0/2514.0/25
Camera and placement4.0/156.0/15
Reflections10.0/1208.0/120
Materials and scale6.0/103.5/10
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-6.1 Terra Low

Six attached outward-facing heads, delicate scales and soft ivory shading establish an orderly decorative motif. Separate paddle-shaped bodies replace the required interlocking loops and leave no enclosed central hexagon. Surface detail provides interest, but repeated simple forms, schematic faces and limited anatomical modeling constrain the result.

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-6.1 Terra LowMuse Spark Open
Task & likeness4.0/105.0/10
Anatomy & construction3.5/104.5/10
Space & placement4.5/106.0/10
Light & reflections5.5/105.0/10
Purposeful detail5.5/106.0/10
Artistry & character5.0/105.0/10
Materials & effects5.5/105.0/10
Visual integrity4.0/106.5/10

Benchmark task

GPT-6.1 Terra Low

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-6.1 Terra Low

A recognizable, coherent portrait with purposeful facial detail, warm local volume and layered scenery. The frontal pose, enlarged face, merged hands and shallow clothing construction substantially limit replication and drawing skill. The visible successes support retaining the current assessment.

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-6.1 Terra LowMuse Spark Open
Task & likeness5.0/103.0/10
Anatomy & construction4.5/103.0/10
Space & placement5.0/105.0/10
Light & reflections6.0/104.5/10
Purposeful detail5.0/104.0/10
Artistry & character5.5/103.0/10
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-6.1 Terra Low

A coherent sunset scene demonstrates the beach, animals, birds and reflections. Flowing silhouettes, warm color transitions and intact attachments are its strongest properties. Simplified anatomy, the turtle's elevated viewing angle and symbolic surface effects constrain drawing complexity and physical depth.

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-6.1 Terra LowMuse Spark Open
Task & likeness8.0/108.0/10
Anatomy & construction5.5/106.0/10
Space & placement5.5/106.5/10
Light & reflections6.5/105.5/10
Purposeful detail6.0/106.5/10
Artistry & character5.0/105.5/10
Materials & effects5.5/106.0/10
Visual integrity7.5/108.0/10

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-6.1 Terra Low

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-6.1 Terra Low

Recognizable animals, a coherent craft and sweeping wake make an appealing cartoon. Basic limb construction, weakly demonstrated raccoon seating and limited shared perspective constrain the scene. Small identifying details work well, while lighting and materials remain broadly graphic.

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-6.1 Terra LowMuse Spark Open
Task & likeness6.5/104.0/10
Anatomy & construction5.0/103.0/10
Space & placement5.5/106.0/10
Light & reflections4.5/104.5/10
Purposeful detail6.0/107.0/10
Artistry & character5.0/103.5/10
Materials & effects5.0/105.0/10
Visual integrity6.0/105.0/10

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-6.1 Terra Low

A coherent coastal illustration with a distinctive pelican, controlled contours and clearly organised bicycle wheels. Visible saddle support and shaped neck and wing contours earn credit beyond basic geometric construction. Rubbery legs, unresolved pedal contacts and absent steering contact limit the riding action. Lighting and materials remain restrained and spatially shallow.

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-6.1 Terra LowMuse Spark Open
Task & likeness7.0/107.5/10
Anatomy & construction5.5/105.0/10
Space & placement6.0/106.0/10
Light & reflections5.5/105.0/10
Purposeful detail6.5/106.5/10
Artistry & character6.0/105.5/10
Materials & effects6.0/106.0/10
Visual integrity6.0/107.5/10

Benchmark task

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