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Havok is by far the most superior physics engine there is to date.



Superior is a bad word - popular yes, but not really superior. There are a lot of 3rd party physics engines which are more accurate than Havok (which is mostly built to just make people laugh at the way the bodies fall over).

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However I very much doubt how it would implement with 3dgs. Might be possible, but I doubt it.



If you have the money for Havok (or one of the other high dollar engines) integration is not a problem. Not only will their customer support people work with you to ensure their product performs well in your game (otherwise it looks bad on them) but you also should be able to put a body on the task of integration. It should be no harder than the task which Newton did integrating his engine with 3DGS - and he pulled that off in record speed.

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Rag-Doll for all bi-ped models, including the player and enemies(though this may not be player in the usual GS terms).



For this I either Newton of the GS PE should work equally well. You will need to develop a method of affecting the model with hinge constraints though. You should be able to script it to work on bones - though you could also use a segmented model as opposed to single mesh.

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Material/Fabric that moves accuratly, i.e hanging drapes that move as models pass through it. (Presume this uses bones/key physics points to animate).



Create your own. This is hard to do with a physics engine, and is generally better off handle by a custom deformer which acts as though it were real physics. If you wanted to get crazy though - you could create a latice using vertices and collision bodies which react to player movement. However for things like hair/clothing - there is no air to react with - so you will need to be a bit more creative here.

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Moving water surface, as with the fabric above, but with ripple control, i,e as objects more through the model, waves are created. (I am not talking about graphics that create the illusion, but actually moving the water surface (as seen in the title Prince of Persia for PS2), according to interaction.



I remember reading a white paper on RT fluid dynamics. They are really still in their infancy. While I have not looked at Prince of Persia - my guess would be that it is just really good illusions (shaders and a mesh deformation routine). This is something that has not been (to my knowledge) ever done in any published title.

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Also standard things like object-object collision, weight/mass/velocity modifiers as well other elementary physics are a must. So what route to take? Which Physics engine to use if any of the above?



All of the above. Havok could be integrated assuming you could get it. Newton and GS PE can work both at the same time - so try both and go with the one which handles the task best.

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