Agree 110 % with Pepsi - Max should not be used at ANY stage of the production process if this is to remain 'Open Source'.
The PLASMA Engine does NOT use Max script directly, Max Script is converted into PLASMA Script(based on Blitz3D)
I don't understand why you would want to write a script in Max and then translate it to Plasma script which is based on Blitz code. Why not just write it in Blitz !?!
So - its still a bit vague how you and the end-user are going to create their levels.
The file format that should be used is also unclear.
How will you do the character animation - what format - what animation application.
Tell me to shut up if you like but I can see Project Plasma dying a murky death at least as an Open Source project.
My advice to you would be to nominate one of the Level Editors - probably Maplet as its free - as the official Level Editor for Plasma - forget about all that Max script hoodoo.
(Quill3d would be perfect especially for lightmapping but it ain't free)
Use as much code as you can from the code archives - there you can find FPS camera code, particle systems, shooting code etc.
Have a look at the source to Norc's 'Chateau Pregny' the best FPS for Blitz written to date.
Don't overcomplicate things too much - this will put people off collaborating.
Once again this is not a flame and I totally respect and recognise that you've put a lot of hard work into this so far. It would be a shame if it were wasted. I really feel the suggestions I have made would help to make Project Plasma a reality.
Cheers
Smiff ;)