A pool of short-lived quads, simulated on the CPU and drawn at once: one draw call per emitter, whatever the count. The look lives in a .particles file: how they are born, colour and size over life, gravity, and whether they blend alpha (smoke) or additive (fire and sparks).
Click the game to fire a burst. The rockets add the other two things a file can declare: a trail of past positions, and a children effect fired when each one dies.