Can nodes used for everything?

I wonder if node setups can be used for anything else other than Textures, Materials, Compositing.

I have seen for example the developer of Polydrive use node setups.
www.blenderartists.org/forum/showthread.php?279453-Polydrive-advanced-procedural-polymodeling-remeshing-(-possibly-development-funding)

How can exactly can this work? I mean that a Node setup as far as I know has an output result (image, texture, image buffer) so I don’t know exactly how it can evaluate a script as a scene handler or modifier.

Also I would like to ask if an ongoing project for game the engine called “Hive” or another project to allow node based particle setups. Do these work similarly? Can they access bge and bpy modules?

(double post)

Hive can run on top of bpy. I haven’t created any nodes for it because I don’t know a thing about shading or compositing.
Hive supports “push” evaluation (event-driven, dataflow in the forward direction) in addition to the “pull” (demand-driven, reverse direction) evaluation used by the standard Blender nodes. The advantage is that you can control the state and evaluation order of the nodes. This is also the disadvantage: managing these things is hard, and you have to do it manually, the graph won’t update automatically when you adjust it.

I can’t answer your questions about Polydrive or other projects. I know that Lukas Toenne is working on particle nodes for bpy, and Moguri and Kupoman on particle nodes for the bge. Maybe you could ask them directly on IRC.

You pretty much have to grab the node tree and evaluate it manually in your own code by constructing a node graph (or some other method) since as far as I know the pynodes still don’t have any sort of eval functionality.

I guess that what I am looking for is PyNodes right?
http://wiki.blender.org/index.php/Extensions:2.4/Py/Nodes/Cookbook