At the same time, have you noticed that like 98 % of the UE3 titles prefer to use default PhysX integration ? Even the AAA games, that can easily afford Havok license - Mass Effect series, Gears of War series, Batman series, Bulletstorm, Dishonored, Mortal Kombat, etc. I remember only several UE3 games with custom Havok physics - Wheelman, StrangleHold, Golden Axe: Beast Rider.
Irrational Games in Bioshock: Infinite used custom PhysX 3 integration in UE3, despite the fact, that the team had big experience with Havok in Bioshock/Bioshock 2
When Havok released a free Havok Physics license for PC in 2009 (sponsored by Intel, Havok Animation included), why hasn’t it became popular among mid-range developers and killed PhysX, if it was so good ? (there are only few decent indie games with Havok, namely Spintires and Space/Medieval Engineers).
This bring us to an interesting dicussion, but it is completely off-topic.
Actually, nothing prevents you from using Havok with UE4 right now. Just pay $$$ for the source license, and they’ll probably integrate it by themselves.
The only middleware that gets Havok for free is their own Vision engine.
Those were using PhysX. Before Havok has bought Vision engine from Trinigy, it had strong PhysX integration, preferred by most developers.
This led to a curious situation, when Orcs Must Die 2 had both Havok and PhysX logo on their title screen
Indeed 