I want to create a particle system for gore effects. I have some requirements that don't seem possible with Unity's built-in particle system, but I want to make sure I haven't overlooked something. So the question is, can this (the following) be done with the built-in system or will I need to implement a custom system?
I want the particles to be made of hand-drawn pixel art. The art has specific sprites drawn for the eight cardinal directions. The particle system uses an angle to choose which sprite to use.
For a blood splash effect, the particles are drops of blood. The angle of trajectory is used to select the particle's sprite each frame.
For an explosion of bones, the particles are twirling bones. Each particle has some intrinsic rotation as well as rotational velocity. The angle of the intrinsic rotation is used to select the particle's sprite each frame (independent of the trajectory).