Hi, I've made my first map of the Netherlands. (not public yet) It has 427 territories and some are very close. The help advises 900x900. Is this the max size for a map?

900x900 is the suggested size, not maximum.

It's important to realize that SVGs work a bit differently from pixel-based image programs when it comes to size. Since the data is represented as vectors instead of pixels, the size is actually irrelevant. You could fit 10,000 territories into a canvas that's only 50x50, and you wouldn't lose any quality at all - you'd just have to zoom in, and zooming doesn't reduce the quality at all.

However, WarLight places a significance on the size. WarLight automatically zooms the map in our out to fit the player's screen size. Therefore, if you make your map bigger, WarLight will have to zoom it out, and this zooms out the army numbers and attack arrows making them smaller.

900x900 is the recommendation for a map where the user does not need/want to zoom in to play. Some maps, like Quad Earth and Big USA just assume the user will zoom in, therefore their maps exceed 900x900 by a lot.

The bottom line is, try your map. If you find the army numbers and arrows are too small, then your map is too big. If the army numbers and arrows are too big, then your map is too small.

Does this help?