Do you have ‘Responsive AA’ enabled on the material for the rain particles?
Hey there!
I’ve started setting up my own particle systems with materials, for games/archviz. However when I’ve started making the rain particles, I’ve encountered a few problems. First of all, everything was working correctly with a snow particle system, and I am mostly using the same setup. My problem is actually the rendering of the particles. No matter how many particles I set, it just looks empty and dull. For example, in the picture you can see 60K! particles rendering in a 100x50 location. I do not know what can cause this problem. Everything is set to epic, I’ve tried starting it as a standalone game, or just in the editor, nothing seems to work. Also the particles are not even showing up properly (not even close to what you see in the picture), even tough I use GPU particles, and the boundings are set perfectly. Again, this is not happening with the snow particles, only the rain, and I do use mostly the same setup. Any ideas?
REMINDER ++ YOU SEE 60K PARTICLES ON THE PICTURE ++ REMINDER
It’s only by the windows on x,y - 100,50 location 
I didn’t have. To be honest I didn’t even know there’s such a function 
Anyway, it made it a lot better. Thank you for the suggestion