HL2 is not a modified Havok engine, it uses the Havok engine for physics, that's it. And Havok has just been dropped in and modified to work with HL2, its been recoded up the ass to exceed the ability of the havok engine. It is a revolution as far as physics are concerned because they spent the extra time to make them unique so you can manipulate the environment that will affect the game.
Far Cry outclass Half Life 2? Sorry but not going to happen. Maybe you should play the CS:Source beta before opening your idiotic mouth.
And as usual Tim is showing how stupid he is with his uninformed comments.
BTW, the smoke in CS:S is awesome.