I know there are gimmick maps out there (the Mega Man one, the Moonwalker one) that replace standard sounds, like the killcam sound, to match the map's theme. My guess was that they force-packed .wav files with the same filename into the BSP file and let the game's override system take it from there. So I examined the files in Crafty's File System Browser, and sure enough, there they were. My question is, how much can I hack using this technique? Can I, for example, customize the surface properties data using custom decals and hit/walk sounds? How about overriding the announcer's lines? Models for the engineer's buildings? Particle effects? Where, exactly, does the game draw the line between files it's willing to override and ones it isn't? And does the sv_pure setting play into this in any way?