Particles
Also said as Particle effects, VFX, Dust and sparks
Many small, short-lived sprites thrown off by an event, each with its own speed, fade and gravity: dust on a landing, sparks on a hit.
They answer the question "did something just touch something?" at a glance. They also carry direction and force: a landing that throws dust further felt harder.
Say it
“Spawn ten dust particles at the feet on landing, spreading sideways, scaled by fall speed, each fading out in about 0.4 s.”
Where you’ve seen it
Hollow Knight throws sparks and soul on each nail hit, and Nuclear Throne fills the screen with shells and debris on every shot.
Not to be confused with screen shake
Particles happen at the point of contact, in the world. Shake happens to the whole camera, so it affects everything at once.