desertplat was the first true single player map for CE. It doesn't have any of the hard coded support for a SP level, but it was properly extracted from a CE map, recompiled through the terribly-beta tag converter, and populated again in Sapien. As for true and good single player maps, you wont find many and off the top of my head biohalo is pretty much it. I had a few in the works for that old campaign of mine where I had a spartan team inserted into the far side of covenant space, but not being able to get the monitor animation graphs to convert ultimately killed Project Euclid. I actually thought of trying to revive it here recently, butCE is soo old and I could just as easily turn it into a new IP and stick it into something like Cryengine2 or Torque.