[ODE] Physics in halflife 2

[Joakim Eriksson]

Just noticed the E3 game fotage for halflife 2 and all I can say is ..
wooww, dude.
That's some cool physics. Apparenly they use havok for thier physics
and that got me wondering how havok actually does its physics.
In the lack of a better place to ask I though someone here might known.

Do they use standin collision objects? (Like cylinders and boxes)
Is the world triangle based or do they have some simpler collision
dynamics to simplify the world-object collisions?
Lastly do they use the timesubdivition method (That is so they dont 
need the collision to report penetration depth but just
a simple if the object intersects or not) or do they allow
interpenetration?

/Joakim E. - http://www.planestate.net