The maps are stored in Unciv/maps/ you can open the folder to manually import and export maps. You can also use the “Copy to clipboard” and “Load copied data” buttons. You can find a lot of maps to import in the discord. To publish your map, you can put it in a mod, or send the map file in the discord/reddit.

The map editor has a lot of tools in multiple categories :

• View : Allow you to set a description and see the percentage of water and impassable tiles, and the number of continents.
• Generate : Allow you to generate a map or to only generate one step (such as landmasses, ressources or vegetation).
• Edit : Allow you to manually edit the map tile per tile, you can edit anything, even add improvements (such as farms and mines) and starting locations (so players start at the right place depending on their civs)
• Load : Self explanatory
• Save : Self explanatory
• Mods : Allow you to use mods for custom tiles, nations and generation.
• Options : Allow you to import and export maps, change tile matching criteria and more importantly, choose an overlay image.

I strongly recommand to use an overlay image when you can. If you do a real world map, try using multiple, one with altitude, one with temperature, etc…

What is tile matching criteria ?

It determines whether you can place something. Example: You have a tile with a grassland + hill + forest with complete match, the game won't allow you to place a desert, because desert and forest don't match. with base terrain only setting, you can place the desert, removing the forest in the process.

• Topmost setting checks for complete match, meaning you can't replace any base terrain/feature/improvement/resource if they can't match all other base terrain/feature/resource/improvement
• Second setting means it ignores improvements when checking and just removes the improvements if they don't match
• 3rd setting also ignores resources, so it removes them as well if they don't match
• 4th setting also ignores all features, removing all mismatching one.

Another important note: The tile matching criteria setting is also used for the floodfill option

(Credit to bamboolord on discord for this)

(Credit to aiinx on discord for this image)