As a developer, it is currently too hard to make good looking bullets and sparks from particle emitters simply because if the texture used for the emitter isn’t a symmetrical shape like a square or circle, it looks all wonky because no matter which way the emitter is facing the textures always come out facing up.
I propose an option to lock the particles on all rotation axis except for the primary axis which would be the axis that is going from the emitter location to the particle location. This would work similarly to how trails work in that when face camera is enabled the trail segment is allowed to rotate on its primary axis in order to face the camera.