In version 3.02, the save files are located here:
Windows: %localappdata%/IIslands_Of_War
Mac: ~/Library/Application Support/com.jwiggs.iislandsofwar
Linux: ~/.config/IIslands_Of_War
In the next update coming soon, I figured that once people have had their fill playing normally, they would want to try and mess around with the game, so I have added some nice tools to let the player do that.
Enjoy!PS. (shameless plug): You can also join the discord server here: https://discord.gg/c3NQd47 to get test versions of the game.