Instead of turning off the shape module and setting the render alignment to velocity, I turned the shape into a box with aligning it to direction, which on my first test within the prefab editing view seemed to work fine…
Another thing I did (and I did keep this difference) was that I gave the particle system a slight nudge and a tiny bit of gravity in order to give the bolts a bit of a ballistic flight. Not too much (only -5 to -10 ° on the X axis, and a gravity modifier of 0.1) so the bolts won’t fly over the enemies’ heads. Just enough that it somewhat corresponds to the particles’ lifetimes and instead of just vanishing into thin air they give an illusion of hitting the ground.
With a speed of 30 the effect gets somewhat lost, though and the playing field is too small for the bolts to reach the ground at the moment (and possibly it needs some more tuning as well)…
And I could imagine if one wants to add more complexity to the game later on, one could have towers that fire some missile high into the sky, and while they can’t target directly adjacent tiles, the impact of their missiles could be much stronger when they hit from above. (And one could have different enemy types and some of them being stronger on their sides but weaker on their top, and vice versa…)