Faithful port of the Unity CRAB MOT mini-game. 16 elements per trial,
2-5 targets distributed [2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5] x 16
trials/form (x 3 forms A/B/C) plus 2 warmup trials. Probing 2 s,
color-fade 0.1 s, tracking 6 s, soft 10 s, mid 20 s, block 300 s.

Hand-rolled Canvas engine: rejection-sampled placement, constant-speed
integrator, elastic disk collisions, perturbation rule (1/30 s tick,
40% chance per axis with +/-0.5*randSign scaling, renormalised).
Highlight one element after motion stops, "Blue (was target)" /
"Yellow (was distractor)" 2-AFC response.

4 locales (FR/IT/DE/EN) verbatim from Unity I2 under _MOT/mot_*. 112
OGGs (28/locale) shipped from Assets/Addressables/VoiceOver/MOT/, with
Replay button per narration card. Forms A/B/C selectable on welcome.