Apart from quake3, what are the other engines that uses volume based representation for navigation

- Doom 3
- official Counter-Strike bots (by Mike Booth, Turtle Rock Studios, see his GDC2004 presentation at http://www.gdconf.com/archives/2004/index.htm )
- Command & Conquer: Renegade (see GDC2002 presentation by Patrick Smith, http://www.gamasutra.com/features/20020405/smith_01.htm )
- No One Lives Forever series (Jeff Orkin?, client side source code available)

I suspect Deus Ex 2 and Thief III may also use navigation meshes, given Paul Tozour's involvement and his articles on this topic in AI Game Programming Wisdom.

Speaking specifically to volumetric pathing representations (versus plane based nav meshes)

While NOLF1/NOLF2/Tron 2.0 did use volumes, little of the code used the volumetric properties. For the most part, axis aligned volumes were used as planes. My guess is that originally, the use of axis aligned volumes had more to do with them being an engine/tool primitive than specifically wanting this feature.

(Side node - to my knowledge, Brian Long was the original author of the volume system used in that series of games. Jeff Orikin did significant work refactoring and extending this system for NOLF2).

I don't have Mike Booth's paper on hand, but I thought they used connected planes, not volumes?