shaders
--done *sort of*, first iteration of the blender previewer had "shaders" (my custom ones, bloom, motion blur and nightshade)
particle system. not done (not well at least)
--not worth doing in blender, but lets see when 2.5 come out if the particle system would be robust enough for the game engine
similar ragdoll physics. not done (i suck at this)
--
done, but with horrible results (amusing though)
importing replay files (models, animations, flames). not done (flames not needed but wanted):
--probably the easiest one. did this back last year. if i remember where i put the sourcefiles, i can recreate it with environment and body mods.