   Map files... what's good to start with?
  So, I think I've got a decent-enough framework up that its time to start finding a way to get a world into my game. I'm using C#/MDX. A few people have recommended Quake 3 BSPs, others have said heightmaps/terrain generation. So, any tips/advice?   
  It really all depends on your game type.  For a fps you would want to use bsp's.  There's enough documentation on the net to implement that. Heightmaps are useful usually when your game will be outdoor with wide open spaces.  Heightmaps tend to look more fake though if you don't know what you're doing.  There are many other alternatives.  One could even create a level in 3ds max or maya, but you would have to create a pretty good visibility determination algorithm so as to not bog up the game.  Another alternative would be to actually create your own level format and editor.  One that could create simple terrain, and import buildings, objects and such, and maybe a simple scripting engine.  Well that's about all I can say, but there some other alternatives if you do the research.