@GoEatATowel Unfortunately, the source engine would not allow us to make it as was intended in my concept art. The source engine just does not work the way we wanted it to. I wish I could explain it better, but unfortunately, explaining it better is out of my skill set. In the future, I'll try to make ones that are not as difficult to pull off as open-heart surgery.

It would be extremely hard to intentionally sync a rotating spritesheet to how quickly it orbits and would be guaranteed to eventually desync and look even weirder if given time

Just another additional comment, wouldn't it be possible to model two 3d biplanes with simple shading in blender, capture an animation of them rotating, and then apply that to an orbit effect?

I think you can adjust the unusual to be over your head if it is added in game, but I'll have to double check that!

move it over the head i'll think it would look better that way but it looks real cool

I would suggest then having them oriented where one is chasing the other, or if possible having animated sprites that have turning animations (think like Doom's sprites and how they function as 2d objects that change sprites from different perspectives). It would be simple enough to animate it and key it with the speed of the rotation so it looks like a plane constantly making a banking turn around the hat.

hmm we've tried rotation flips for the plane sprites early on, but it was later scrapped for looking weird.

Given that this was made by a team of people, I want to try and refer this comment to the artists and the particle creators and riggers.

Having the orientation of the planes be static makes it a little awkward to watch. It is a neat concept for an effect and it's hand-drawn, which is really neat! However, again, that locked orientation makes it seem a bit goofy. If you want my opinion, I think it may be a better solution to animate the planes chasing one another, with the target plane pulling a maneuver (such as a canyon turn), the hunter then having to pull the same maneuver, then flying in the other direction. I do not know much about blender or the limitations for unusual effects to be animated to that extent, but in its current state it could use a little more something.
However, if that's not a viable option, I would highly suggest changing the bi-planes into helicopters. Other than that, I think this is neat but a little awkward. Keep up the hard work, and let's see where you can take this effect.

screams in 2D image GIFs