I'm curious myself. I seem to remember that Havok did have a subset of functionality that could do deterministic physics, which was interesting at the time.

TBH, it is probably hard to compete with the likes of PhysX and Bullet these days. I imagine even MS doesn't know what to do with it. I would hope that they would just open-source it rather than abandon it. Perhaps they are working on something big in secret that uses it.

Why don't you ask?

https://www.havok.com/contact-us/

Zelda: Breath of the Wild shipped using Havok on the Switch last year, and other 2017 games used it on PC, PS4, XbOne. So seeing MS acquired the company back in 2015, I would assume that they didn't do the stupid thing of stepping in and stop them from supporting other platforms. The sales page that I linked to also still says that they support all these platforms

Anyone who has a "contact us" for instead of a price on their sales page, in my experience, typically tailors their price for each client instead of having a fixed price. They might charge differently depending on your budget/size, number of platforms, number of games, number of sites, level of support, etc...

The open-sourcing of PhysX probably really put the squeeze on them, I would imagine... making it much harder to sell that kind of product for a large sum. Before PhysX went free, I had heard of people paying ~$30k USD for it.

PhysX is in both Unreal and Unity. We use it too.

However, if Havoc has deterministic features it might be worth licensing, especially if you are doing multiplayer networking. We use PhysX, and keeping the bandwidth down is hard: http://demo.kinematicsoup.com is an example.