STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Muse Spark 1.3 vs Step 5 Preview

Muse Spark 1.3 leads Step 5 Preview by 0.8 points on StealthMark, 39.8 to 39.0. It leads on 6 of 9 benchmarks, including both games, and Step 5 Preview on 3. Step 5 Preview scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

39.8/100Overall rank 34/53
39.0/100Overall rank 36/53

General Intelligence

38.3/100
37.1/100

Visual Intelligence

42.3/100
41.9/100

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

BENCHMARK BY BENCHMARK

Where each model leads

  • Muse Spark 1.3
  • Step 5 Preview
  • Other models
  • Median

DATASHEET

Specs and pricing

Both take about 1M tokens of context.

  • Muse Spark 1.3
  • Step 5 Preview
  • Other models
  • Median
PricePer 1M output tokens, input below
Muse Spark 1.3: $4.25$1.25 inputStep 5 Preview: No list price
Context windowTokens per request, max output below
Muse Spark 1.3: 1MTiedStep 5 Preview: 1MTied
Output speedTokens per second, our measurement
Muse Spark 1.3: 321tokens/sStep 5 Preview: Not measured
SizeTotal and active parameters
Muse Spark 1.3: Not disclosedStep 5 Preview: 600B27B active
Developer
MetaStepFun
Released
2 Sep 2026Not published
Origin
United StatesNot published
Input → output
Text, image, video, audio, PDF → textText, image, video → text
Architecture
Not publishedSparse mixture-of-experts; 92 layers (88 MoE), 352 routed experts with 8 selected per token plus a shared expert; grouped-query attention with 512-token sliding windows and full attention every fourth layer; 3 multi-token-prediction layers; vision tower for image and video input

Full datasheets, every price and sourceMuse Spark 1.3 ↗Step 5 Preview ↗

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.

Muse Spark 1.3 64.3/100Rank 6/49

Survived 2 of 3
Foresight: complete playing field
Level 311 ptsTurn 17 / 20

Step 5 Preview 59.9/100Rank 42/491 of 3 levels

1 of 3 played
Foresight: complete playing field
Level 122 ptsTurn 28 / 28

Points per level

LevelMuse Spark 1.3Step 5 Preview
Level 1Second Thoughts
26 ptsSurvived
22 ptsSurvived
Level 2Pressure Pot
10 ptsSurvived
Pending
Level 3Hide or Flight
11 ptsOut of lives
Pending

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.

Muse Spark 1.3 72.4/100Rank 27/503 of 5 levels

3 of 5 played
Latch: complete playing field
Level 318.8 ptsTurn 32 / 36

Step 5 Preview 40.7/100Rank 28/50

Cleared 4 of 5
Latch: complete playing field
Level 515 ptsTurn 35 / 40

Points per level

LevelMuse Spark 1.3Step 5 Preview
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.8 ptsCleared
9 ptsCleared
Level 3Relay vault
18.8 ptsCleared
18.6 ptsCleared
Level 4Passing bay
Pending
15.6 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
Not played
15 ptsFinished early

Newton's Mirror

Same task instructions

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

The judgment

Muse Spark 1.3

The paint state is incorrectly and poorly drawn, despite a recognizable sphere-and-paint setup. The oversized sphere, oversized compact paint bodies, and blurred wall and floor images further limit the result. Isolated reflection cues provide very little support for the required repeated virtual rooms, nested spherical imagery or emitter mapping.

Step 5 Preview

The main sphere, airborne black and small colored features occupy broadly appropriate positions. Most of the defining mirror system is absent, and paint interaction remains only partially supported. The small paint features do not visibly establish a separate volume-scale violation.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
State at 600 ms6.0/2520.0/25
Camera and placement8.5/1513.5/15
Reflections5.5/12020.0/120
Materials and scale4.0/107.0/10
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

Muse Spark 1.3

The luminous creature and geometric mirror counterpart communicate self-recognition through a coherent palette and expressive eyes. The transformed reflection is purposeful. Simple oval anatomy, ambiguous reaching-arm construction, shallow spatial staging and limited illumination of nearby surfaces keep the illustration below exceptional execution.

Step 5 Preview

A charming diagonal climber and warm palette communicate the central idea. Simple rounded construction, crowded limb counting, uncertain footholds and an unattached upper shelf limit its physical coherence. Growth bands and the yarn trail add specificity, but the requested material distinctions and unravelled bootie remain underdeveloped.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
Task & likeness8.0/106.0/10
Anatomy & construction5.0/104.5/10
Space & placement6.5/105.0/10
Light & reflections7.0/105.5/10
Purposeful detail6.5/105.5/10
Artistry & character5.5/105.0/10
Materials & effects6.5/106.0/10
Visual integrity7.5/105.0/10

Benchmark task

Muse Spark 1.3

An imagined creature encounters its reflection. The scene tests original character design, visual self-interpretation and the relationship between a subject and its reflected image.

Step 5 Preview

Character scenes test expression, anatomy, materials and coherent visual construction.

Mona Lisa

Same task instructions

Precise visual recall and portrait reconstruction.

The judgment

Muse Spark 1.3

Dark hair, a restrained smile and overlapping hands suggest Mona Lisa, but replication is weak. The face is markedly elongated, the hands are oval pads with faint finger strokes, and the atmospheric landscape is absent. Soft gradients provide basic volume, while the frontal symmetry, shallow space and sparse clothing detail limit the portrait’s drawing quality.

Step 5 Preview

A recognizable, coherent simplification with purposeful facial contours and differentiated fingers. These provide more construction and detail than the broad silhouette alone suggests. The oversized face, frontal seated pose, unresolved wrists and sparse landscape still substantially limit likeness, depth and finish.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
Task & likeness1.0/104.0/10
Anatomy & construction1.5/104.0/10
Space & placement1.5/104.0/10
Light & reflections1.5/103.5/10
Purposeful detail1.0/104.0/10
Artistry & character1.5/104.0/10
Materials & effects1.5/103.0/10
Visual integrity3.0/103.5/10

Benchmark task

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

Beach

Same task instructions

Creativity, perspective and visual beauty.

The judgment

Muse Spark 1.3

The warm sunset, framing palms and colorful beach accessories create an appealing scene with the requested animals, birds and reflections. Construction remains schematic: the raised hand misses the kite string, and a doglike silhouette hangs above the water without clear support. The sun reflection establishes a focal path, but shadows and materials lack depth. An unexplained horizontal bar crosses the sun.

Step 5 Preview

A recognizable sunset beach with clear warm-cool contrast and playful accessories. Basic animal construction, shallow foreground placement and schematic reflections limit spatial and physical credibility. Sparse descriptive detail and abruptly ended sky bands constrain the finish.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
Task & likeness6.5/104.0/10
Anatomy & construction3.0/103.0/10
Space & placement5.5/103.5/10
Light & reflections6.5/103.5/10
Purposeful detail5.0/103.0/10
Artistry & character3.5/103.0/10
Materials & effects3.0/103.5/10
Visual integrity3.5/104.0/10

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

Muse Spark 1.3

This benchmark has not been assessed yet.

Step 5 Preview

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

Same task instructions

Scene composition and interacting subjects.

The judgment

Muse Spark 1.3

The raccoon clearly rides on the dog's back, and the dog's paws reach the jet ski controls. Expressive faces and bright colors make the scene appealing. Simplified joints, crowded steering geometry and shallow hull perspective limit construction. The sun has no corresponding water reflection, and the splash shapes convey speed more clearly than convincing displacement.

Step 5 Preview

Recognizable animals, a bright palette and identifying accessories support a basic cartoon. Primitive anatomy, partial seated support, unresolved steering and weak hull-water contact limit the central action. Lighting and spray provide atmosphere without establishing convincing physical depth.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
Task & likeness8.5/104.0/10
Anatomy & construction6.5/104.5/10
Space & placement7.0/103.0/10
Light & reflections5.0/103.5/10
Purposeful detail6.5/104.0/10
Artistry & character5.5/103.5/10
Materials & effects6.0/103.0/10
Visual integrity7.5/103.0/10

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

Same task instructions

Subject construction and spatial relationships.

The judgment

Muse Spark 1.3

The pelican and bicycle are immediately recognizable, with an expressive face, bold bill and cheerful composition. Both legs connect to the body and reach pedal-like supports, but articulation, saddle support and wing contact with the handlebar remain unclear. Wheel alignment and layering are coherent. Simple landscape shapes, generic shadows and limited material variation constrain the finish.

Step 5 Preview

The pelican and bicycle are recognizable, with a pleasant palette and basic diffuse shading. The riding relationship fails physically: the bird is unsupported, the front wheel is unmounted, and pedalling is unresolved. Simple geometric construction and sparse material treatment further limit the drawing.

Score breakdown

CategoryMuse Spark 1.3Step 5 Preview
Task & likeness8.5/103.0/10
Anatomy & construction6.0/103.0/10
Space & placement7.0/103.0/10
Light & reflections6.0/103.0/10
Purposeful detail7.0/104.0/10
Artistry & character5.5/103.0/10
Materials & effects6.5/103.0/10
Visual integrity7.0/102.0/10

Benchmark task

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