How do I include (and use) custom files in my build (not .txt files)?

I have a set of files that I need to include into my build, and as far as I can tell, Unity doesn’t handle my use case.

Here’s my situation: I have a series of text files that describe tiles that are used in my game. The files and directories look like this:

        [and so on]

At runtime, when run from the editor, I load the files from Application.dataPath, and this works fine. When built, it does not work.

The (partial) solutions I’ve considered:

  1. Using Resource.Load() in the way describe above. This is undesirable because the .let files are generated by a different application, there are lots of them, and they change all of the time. There does not seem to be a way to create a TextAsset unless it has a .txt extension, right?

  2. Using a postbuild step to copy the necessary files over into the data directory. Evidently, there used to be a feature for this (from this question), but the links are now broken, and I can’t figure out the replacement. Besides, does this work in Unity Cloud build (which I use)?

  3. Loading the files at first run from a server, and writing them into dataPath, or someplace similar. Really? Do I really need to resort to this?

This seems like standard blocking and tackling to me. Is there not a better way?

It turns out that this IS standard blocking and tackling. You just need to use the StreamingAssets folder, instead of the Resources folder.

Documentation available here.

This question was also pretty useful, and has some good links about this.