Comet

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Forty thousand particles

The Amiga demo-scene comet was a clever trick. A handful of sprites, multiplexed across scan lines, palette-cycled to fade — a flickering smear that read as a tail because the eye is generous. The total "particle" count was generally tens, and they were less particles than animated dots in a chase pattern.

This one has 40,000. Each particle owns a position, a velocity, an age, and lives in a floating-point texture on the GPU. The comet is treated as an emitter — each particle inherits a fraction of the comet's velocity at the moment of emission, plus a backward-biased breakoff vector, and drifts on that trajectory until it ages out. Every frame, two fragment shaders read each particle's state, integrate, age, and write it back. Another renders the lot as additive sprites. Sixty times a second.

The 90s called this approach a "PhD thesis." It is now a few hundred lines of GLSL.