One thing I was wondering, is what is your creation process? I think it would be awesome of others would be able to contribute to extend the set, but right now I could not find anything about how these tiles have actually been created. Also, given the amount of repetition and strict adherence to certain shapes, I guess you may be using some tools or scripts for this? If so it would be nice to include them in the repository.
I'm using Adobe Fireworks, which is (almost) abandonware. While I'm usually all for sharing source files and merging pull-request, I have a feeling I would reject 99% of PRs for this project (on aesthetic grounds ), so I'm not sure there's much point. It's also all in 1 file, and I would like it to stay that way. I'm slightly tempted to create a generator for the base-tiles though.
Another thing I wondered is why your tiles are so large. But maybe that's just because I don't have a 4k screen. I have to scale down to 25% or less in Tiled for reasonable exploration of a map. Given the style of your tiles, would it make sense to distribute them also as SVG? Though I did notice a little noise pattern.
I started working on the tileset on request from @ftomassetti, and he wanted PNG. I wanted the tiles big enough to contain elaborate decorations, so we ended up on 256px. I thought it would be better to zoom out than never being able to see details, and it didn't seem to impact performance much. I could perhaps export them as SVG at a later point if there's demand for it.
I have personally no requests, but doing terrain transitions could make the overall thing prettier. However, I'm sure that'll get a little much in combination with the height changes, unless some restrictions are applied.
Yup, that's pretty much suicide
I made some transitions for flat-tiles only, but I have to admit I kinda like the strictness of not having transitions too.