Once you have your config.bmp properly setup, you can now begin the process of editing all of the city tiles to create the terrain that you want for each. This could take a few hours or a few days, depending on how much time you lavish on tiny details. When you start, you'll have a completely flat field of water or plains (depending on which you picked when you created your custom region). Each of those tiles now has to be seperately edited. My preference is to start by laying out the base altitudes of my various city tiles as shown here:



As you can see, I'm planning a mountainous area in the middle of the right side. Now, word of caution here, if you make a foreground tile too high, you won't be able to see the smaller ground-level tile behind it (and SC4 does not let you rotate the region view). So work from the back to the front, and don't get too crazy about tile altitudes. I created mine by going into each city, clicking on the God Mode icon in the lower left (the sun), then Terrain Effects (blowing cloud), then clicking the Raise Terrain Level a pre-determined number of times. (The really high tiles in the view above were about 15-20 clicks of the Raise Terrain Level button.)

Here is what the region looked like at various points so far:









Now at this point, I had a problem. If you look closely at the upper image, you'll see that the terrain is raised above the base and there is a gap between the two (seems to be some sort of SC4 bug). The fix was rather easy (fortunately) - just edit the tile, then raise and lower the terrain once and it will settle back down onto the base (see the next image below).











When you first create your tiles, try to match up corner heights by creating valleys or hills, but don't use Reconcile Edges until you have to. The RE command is both a blessing and a curse. My usual plan was to get things as lined up as possible by looking at things in the region view, then go into each tile, use RE, then use the Soften terrain tool on any corners that got pointy. Eventually, as you make your way around the map, you'll manage to get everything lined up. It just takes a while, it's not seemless or easy.

I'm also not sure yet how well some of these tile designs will work (mountains with no water source) for placing cities on. The samples that came with SC4 were all pretty flat. I'm guessing that the inland tiles can build wells or trade with other tiles for their water needs.