like here are a few questions to start: do you have the correct resolution size on your color map texture? All of the textures you load into Cities must be at the smallest 256 x 256 in resolution or a power of 2 of 256 (like 512x256 or 512x512 or 1024x256 or 2048x512 etc.)

Your textures that are loaded into the import folder for Cities must have suffixes telling the game what type of texture it is. "modelname"_d for diffuse "modelname_s for specular etc. You must drop a copy of those PNG/JPEG images into the import folder or Cities won't know what to put as far as texture on your model.

If you want to share your blend file and texture I can take a look - not a pro or a expert by any means but I've got the basic steps at texturing something at least so it will appear in game. Usually this stuff entails super simple options that are not selected that should be.

Outside of that I'm not sure what else I can do to help without seeing more of your Blender scene and settings. Maybe if you can't share the .blend file or texture take a ton of screen shots of your blender windows and settings so we can take a look. Once you get the basics down it's easy to reproduce every time...

I tried some things last week, and none worked. I won't be making any mods until I can get the blasted thing to work.

I'll try that sometime in the week. Thanks for the suggestion.

Have you tried flipping your normals? Your normals flipped backwards will do that when you load it in the game. Blender may not make it that obvious but it will be when you load it in the game. Check that out and see if it works. Here is some info that may help:

http://blender.stackexchange.com/questions/12165/make-all-of-the-faces-flip-to-the-right-direction

Pretty sure it's a bug as the faces go invisible when I try to add texture.

No worries [FF]Aperture - was just curious what that meant. I too use Blender, am nowhere near an expert, but have managed to get texturing models down and importing them into the game pretty well. My models suck and my texturing is mediocre at extra best but I would be more than happy to help see if I can make the process a bit easier for you. That is unless you are dealing with a more bug-type issue rather not sure how to flow a model from blender into Cities.

It's a little hard, my Blender plays up terribly and my textures aren't working properly. I'm trying to do it, but it's a little hard.

What do you mean by "texture incomplete"? Shouldn't that probably be done before loading the asset as to prevent getting a flat gray building?