Creating completely deterministic collision for a fighting game

Greetings,

I have a bit of an issue. I’m trying to get completely deterministic collision for a fighting game, but I can’t seem to get it *quite *right. The main issue is that even though it is fixed at 60 fps, I need to be able to adjust time dilation at runtime without affecting the collision. The current way I am handling it is through anim notifies; a notify is fired which performs collision checks every .02 ms for the duration of the notify. The collision spawns spheres (at a socket location) and sweeps the area between the current and the previous sphere with extra spheres, and that works fine at 60 fps. As far as I can tell it is consistent and deterministic. The issue is when I change the time dilation, which technically increases the framerate.

One of the images is at .5 time dilation (120 fps) and the other is at 60 fps. As you can see, even though the same number of spheres are being drawn, the location is different, making the collision not deterministic. My guess is that at a higher fps, the time at which the notify fires occurs earlier since it is more accurate.

How can I make this more deterministic? Any help is appreciated.