I'm glad to hear that! The style is very popular in the drawn maps I've seen. I haven't been interested in maps for long and don't pay too much attention to digital map programs. I associate the style with Dyson, as that what I've heard other people do. I first saw you tweeting about the program after I saw Dyson's tweet and the Dungeon Scrawl site says the development began on May 8th, which is why I thought the timeline looked a little suspect. I'm happy to hear that's not the case.

FWIW, I just pulled open my red-box era OD&D books and the maps are all hatched in various styles when underground, but stippled (kind of a grassy texture) to indicate exterior; so e.g. a for a keep in the side of a mountain it would be clear which walls abut solid matter and which are stone.

The maps in the basic set use circles rather than lines for the hatching though.

I was hand-drawing cross-hatched style maps on graph paper in the early 90s when I was a teenager running my own campaigns, and I certainly don't claim to have invented it either..

Mine didn't look quite so good though. ;-)

Yeah, this was kind of my mindset, too. Hatching is certainly an old trick, and I see the "Dyson hatch" is somewhat distinctive - but for me, knowing "old school" maps, it didn't stand out from the other offered styles - and certainly lived up to the promise of "old school" look and feel :)