Heh, you're right. The .biq in the download includes a map that rendermad used for some screenshots. You can fix this pretty easy. Open up Master of Myrror -Light Terrain- with the editor. Go to the Scenario menu and uncheck Custom Map. Then go to the Scenario menu again, pick Scenario Properties, and uncheck Debug Mode. Hit OK, and then save it. That should do it, just start it up in CIV.
I personally like the dark colors, it gives the game a different feel. In my current game, I'm trying out the nature mages for the first time and going for a cultural victory as Freya. Killing some death mages along the way.