Some of them look really good, but others just don't.
You should learn about the moiré effect and try to avoid it when making tiles. Some of your tiles have a moiré effect that is so strong that they are practically useless.
Also, I think the tiles could be lower in filesize. 500 kb per tile is just sick.
Not that I'll claim to know exactly what you mean by "moiré" but I'll work from a presumed standpoint that it has to do with repeated images in the texture,
so that when one uses exclusively one texture, one gets a strange and not so very pretty effect.
Now, if this is a correct presumption, do regard the following, if not, completely ignore it and slip a note to me with the explanation of the word.
I don't honestly understand why one should care about repeated textures, as well as I do not honestly understand why one should use any texture "exclusively"
and "solely" at any point in any map, the beauty of tiles is to mix them together to get a natural underbrush in any terrain, with a artsy touch.
I also have to say that I disagree about the filesize, but then that's my Terrain Art side being biazed; As it doesn't care one slick of a split second for file-sizes at all,
though Nan0's guidelines as to how to improve them on your own seems legit.
Finally, I'd like to say that I've loved your tiles, Nan0, ever since that "Daemons Paradise" terrain, and can honestly say I've not used any other tiles ever since. And now
you come here, and drop a damned bomb of tiles in the same style and perfection as the previous one?
I'd say a prayer and kiss your boots, but then, I'm not religious.
- Bravo.