Muse Spark Open 29.4/100Rank 34/47

STEALTHMARK · HEAD TO HEAD
All comparisons ↗Callstack Apex leads Muse Spark Open by 5.4 points on StealthMark, 49.5 to 44.1. It leads on 5 of the 8 benchmarks with results for both and Muse Spark Open on 3, including Latch. Pixel Canary scores higher on Newton's Mirror, with its largest category advantage in camera and placement.
See the difference ↘On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.
BENCHMARK BY BENCHMARK
DATASHEET
Muse Spark Open takes 4× more context and runs 41% faster in our speed test. Callstack Apex scores higher on StealthMark and is 42% cheaper per output token.
Full datasheets, every price and sourceMuse Spark Open ↗Callstack Apex ↗
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.

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.


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


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.
Callstack Apex
The principal sphere placement and paint contact sequence are supported. Isolated sphere and panel images provide limited optical structure, but missing lateral chains and side-floor continuations prevent a coherent repeating mirror room. The main and reflected spheres lack ordered curved nested imagery, while sparse planar emitter images and incomplete spherical emitter mapping leave most of the reflection system unsupported.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| State at 600 ms | 14.0/25 | 20.0/25 |
| Camera and placement | 6.0/15 | 13.0/15 |
| Reflections | 8.0/120 | 10.0/120 |
| Materials and scale | 3.5/10 | 7.0/10 |
| Floor-damage reward | 0.0/10 | 0.0/10 |
A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.
Visual construction and creative interpretation.


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.
Callstack Apex
The cheerful yellow bird, cream eyes, orange features and miniature teal console closely match the brief. Clean block edges, restrained colors and soft shadows create an appealing composition. The body reads more like a gridded disc than a fully cubic sphere, and the outlined left wing has limited volume. The right wing reaches the cyan block, though its grip is ambiguous.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| Task & likeness | 5.0/10 | 8.5/10 |
| Anatomy & construction | 4.5/10 | 7.0/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 5.0/10 | 7.5/10 |
| Purposeful detail | 6.0/10 | 7.5/10 |
| Artistry & character | 5.0/10 | 7.0/10 |
| Materials & effects | 5.0/10 | 7.0/10 |
| Visual integrity | 6.5/10 | 7.5/10 |
Muse Spark Open
A small elephant protecting a delicate seed tests expressive anatomy, physical contact and contrasting organic materials.
Callstack Apex
A rounded bird built from small cubes explores a miniature machine. The scene tests block construction, expressive proportions, contact and soft lighting.
Precise visual recall and portrait reconstruction.


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.
Callstack Apex
The framed portrait recalls Mona Lisa through dark hair, folded arms and a hazy landscape. Replication is limited by wide, staring eyes, an elongated neck and a downturned mouth. The overlapping hands lack convincing finger and wrist construction. Soft tonal shading suggests volume, but pervasive blur obscures clothing, landscape and anatomical detail.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| Task & likeness | 3.0/10 | 3.5/10 |
| Anatomy & construction | 3.0/10 | 4.0/10 |
| Space & placement | 5.0/10 | 4.5/10 |
| Light & reflections | 4.5/10 | 6.0/10 |
| Purposeful detail | 4.0/10 | 4.5/10 |
| Artistry & character | 3.0/10 | 4.5/10 |
| Materials & effects | 4.0/10 | 5.5/10 |
| Visual integrity | 6.0/10 | 5.5/10 |
An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.
Creativity, perspective and visual beauty.


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.
Callstack Apex
A cohesive sunset beach illustration with lively wildlife, playful accents, and an appealing warm-to-purple palette. Palm framing and the aligned sun reflection organize the scene, while connected silhouettes keep the activities readable. Schematic joints, ambiguous dolphin junctions, loosely matched reflections, and repetitive surface marks limit construction, lighting coherence, and material depth.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| Task & likeness | 8.0/10 | 8.5/10 |
| Anatomy & construction | 6.0/10 | 4.5/10 |
| Space & placement | 6.5/10 | 7.5/10 |
| Light & reflections | 5.5/10 | 5.5/10 |
| Purposeful detail | 6.5/10 | 7.5/10 |
| Artistry & character | 5.5/10 | 6.5/10 |
| Materials & effects | 6.0/10 | 7.0/10 |
| Visual integrity | 8.0/10 | 4.0/10 |
A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.
Physical reasoning, light and visual reconstruction.


Muse Spark Open
This benchmark has not been assessed yet.
Callstack Apex
This benchmark has not been assessed yet.
A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.
Scene composition and interacting subjects.


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.
Callstack Apex
The raccoon clearly rides the dog's back, and the dog's paws reach the jet ski controls. Expressive faces, a sweeping tail and a strong sunset composition give the illustration character. Limbs remain connected, but the dog's foreleg joints and vehicle seating are loosely constructed. Angular splashes convey speed more successfully than convincing water displacement; lighting and reflections remain decorative.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| Task & likeness | 4.0/10 | 9.0/10 |
| Anatomy & construction | 3.0/10 | 7.0/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 4.5/10 | 7.0/10 |
| Purposeful detail | 7.0/10 | 8.5/10 |
| Artistry & character | 3.5/10 | 7.5/10 |
| Materials & effects | 5.0/10 | 7.0/10 |
| Visual integrity | 5.0/10 | 8.0/10 |
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.
Subject construction and spatial relationships.

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.
Callstack Apex
An appealing cartoon with a distinctive pelican, expressive eye, warm bill and carefully drawn bicycle wheels. The wing reaches the handlebar, but the feet do not clearly engage the pedals, weakening the riding mechanics. Layered hills create depth; limited ground shadows weaken contact. Clean curves and purposeful feather details give the illustration polish.
| Category | Muse Spark Open | Callstack Apex |
|---|---|---|
| Task & likeness | 7.5/10 | 8.5/10 |
| Anatomy & construction | 5.0/10 | 6.5/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 5.0/10 | 7.5/10 |
| Purposeful detail | 6.5/10 | 8.0/10 |
| Artistry & character | 5.5/10 | 8.0/10 |
| Materials & effects | 6.0/10 | 7.5/10 |
| Visual integrity | 7.5/10 | 8.0/10 |
A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.