Hi there 
I would like to do something like that:
Using only particle system. Is it possible? Or should i apply script to particle system and then draw texture 2D?
Use the Limit Velocity Over Lifetime setting to set the Y velocity to zero (enable Separate Axes to do this). Then, change the render mode setting to Horizontal Billboard in the Renderer section. The particles will then spread out flat against the surface beneath them. Naturally, this only works on flat floors