single-pass particle render shader

I want particles to be rendered in a separate layer/pass and then pasted to scene, similar to additive shader.
Sort of like you group layers in photoshop and then set a transparency option to the group itself.


In this example I show AlphaBlended shader, then the look I want and lastly, the look I can get but don’t want (all particles are adding to each other).

Untested, but it sounds like you might be able to achieve this using BlendOp Min with Blend srcalpha dstalpha - Unity - Manual: ShaderLab command: Blend

(That is assuming your background is fully opaque and each of your particles is set to, say, 70% alpha.)