It would be useful to have a “wide” raycast – basically a ray that has a radius rather than being infinitely thin. It would help for auto-aiming and other situations where you want to know about a near-miss. Without it, I’ve been doing multiple raycasts but of course that runs into a sampling problem. I understand other engines have collidecasts, but I don’t know if a fully generic solution like that is really required for the desired effect.
Another useful Havok feature would be an overlap test. I’d like to make a sphere body/shape for one frame to just get a snapshot of what it overlaps or intersects with. For that one frame, the collision callback would just return everything that ephemeral shape overlaps with, and then it could be disposed. Think splash damage checks, area of influence, that kind of thing.