If you hide all but the MAP BORDER layer (layer, not sheet) there is a polygon (probably a decorative frame) on it.

The MAP BORDER layer is a very special layer that determines the extent of the map, controls the behaviour of many drawing tools, and also controls how grids are positioned. The layer should only have a set of 4 green lines, or a green rectangle on it (see below, where I have deleted the other entity to reveal it).

The grid you created was being positioned using the inside corners of that polygon as its origin. If you move that frame(?) to a different layer a new grid should work as expected.

I recommend re-freezing the MAP BORDER layer, once you are done, to prevent accidentally moving or deleting the green rectangle. Take care not to place anything else on it.

Calibre - you might be able to use the 3 shades of grassland as contours.

In the meantime I've realised there's no escaping the necessity of doing all the textures first. Only that way can I draw the mountains and hills to fit the colour scheme. So here are 3 desert textures.

I'll put a SYMBOLS HILLS sheet in the style for the foothills that uses a bevel to generate them from hand drawn patches of Solid 20 bitmap. But I may also do regular hill symbols.

But now I'm more or less happy with the grass, I think I will do some work on the actual mountain before I get into deserts and swamps and stuff - so you get a better idea of the scale of things.

Yes, things are a bit minimal at the moment, but you are largely correct. This will be more of a large region scale... I think.

However, the suggestions made do still shape the decisions I have to make about what to try for ;)

I still think the castles idea would be much better done as a city style, where you can see such details as differences between 2 castles. However, since this is a top view style there's no reason you can't combine structure symbols to make mega cities.

At the moment I'm working on the textures. They always come first, no matter what style I'm working on.

This is a prototype grassland fill. The trick is to get it textured enough to look like what it's supposed to be, but not so detailed that it becomes a fizzing mash of dots. It has to be a suggestion of grass, rather than the grass itself.

Remember the test mountain is the size of a mountain.

I took a break from compasses and scale bars for DD4 to hunt down a very rough untextured test mapped mountain I did back in 2022. Found it, and tried it out.

This is the map file and graphic in Affinity.

And this is what it looks like in CC3.

Obviously, this is just a very basic test, but it's a start.