Texture amount limit per one material? Does Blender Cycles have this limitation? Because I have 63 unique textures inside one emission material and up to 62 textures render fine, plug 1 more - and it all turns into pitch black, both in viewport and final. No crash or slow performance, just blackness.

Textures are assigned to particles on per index base. Same setup in BI doesn't suffer from this thing.

PC specs are: Ryzen7 1700, GTX 1050Ti, 16 GB RAM, Win10
Dirty workaround is to enable Open Shading Language in render tab (works only with CPU), somehow it solved my problem, even though I don't have a clue what does it mean.
Another trick is to use spritesheet technique. In a nutshell, you have to combine all your images into 1 big image (without overlaying of course) and translate UV map along these "small" images. In this setup you are duplicating Vector Mapping as many times as there are images on the spritesheet.