Apart from any 8.0 issues (I'm not a 8.0-user), most gaming environments
like Unreal and Half Life use two types of geometry. I'll use the Unreal
terms, since that's what I have used.
Static Meshes = polygonal geometry, for most imported models (props, scenes,
accessories).
BSP Brushes = boolean operators with geometric brushes, like adding and
subtracting boxes, prisms etc...
A lot of the levels are modelled in software like 3ds max or Maya or XSI and
then exported into the game engine. E.g. to get a 3ds max model (which could
be something that you exported out of Revit as a DWG) into the game engine,
you could export as an *.ASE file, which could be loaded as a static mesh
into the Unreal Editor.
Getting the scale right is tricky and the lighting behaves differently on
these meshes when compared to the internal brush-based geometry, but once
it's imported you can walk in realtime through your model.
Don't expect Revit doors to still be openable doors in the game... Then you
would have to write a custom Revit export plugin, but last time I checked,
Revit didn't have an open API to add this to the program.
--- stefkeB ---
P.S. The workflow from CAD to game is, at best, cumbersome... Getting from a
3D-animation software is the best choice.
P.S.2 - You can also check tools like Cult3D, EON, TurnTool, Quest3D,
Wirefusion, AXEL etc... (the Web3D-tools), which sometimes support
walkthrough features.
P.S.3 - The easiest solution is exporting the Revit model into a VRML file
and using VRML browsers like Cortona or Blaxxun for walkthroughs. Revit 7.0
cannot write a VRML file directly, though, so you should use a conversion
program (or pass through some 3D-animation software that does support VRML).
I tried and by simply exporting the 3D View as a DWG file, I could load the
Revit model in 3ds max 6 and then export it to VRML from there. I can then
walk through the model in realtime (e.g. using Blaxxun as a free viewer).