Projectile Impact Part 1

Add this game-feel effect to my 2D game: Projectile Impact — Impact Spark.

Reference scene (context only — map it onto my own characters and sizes):
A side-view 2D scene at dusk. Pixel art: the hero (12×13 art pixels at 7px, about 84×91px) stands on the left facing right; an orange slime (16×12 art pixels at 5px, 80×60px) faces him 266px to the right, with a 4-segment HP bar (pink #ff5a7a on dark) above it. The view is 438×190px with the ground 34px above the bottom. All sizes are screen pixels at that scale. Times are seconds, t = 0 is the moment the fireball hits. Each second the hero shoots a fireball (a 28px glow, 20px orange #FF7A3D square, 12px gold #FFC24B and 6px cream core) from his hand at t = −0.2; it flies to the slime's front (36px in front of its center, 30px above the ground) in 0.2s with a 14px arc and 3 fading trail copies. On every hit the slime flashes white for 0.07s, squashes 12% for 0.15s and loses 1 HP. The 4th hit defeats it: it turns white, 10 pixel bits fly out and fall from 0.12s to 0.45s, and a new slime drops in from above from 0.45s to 0.7s (easeIn) and squashes 20% on landing.

The effect:
At the hit point draw a white 4-point flash (6px thick bars) that shrinks from 40px to 4px half …

The rest of this prompt — exact sizes, easing, colors and particle counts — and full prompts 2–6 are in the pack.