Hi- Yes, you can use them in unity. There are no engine restrictions on the itch.io version.
As for the world map, here's some examples:
http://chaingame.net/images/up/1634874666_OfLN40IfJY.png
http://chaingame.net/images/up/1634874642_LY6mEi75Sg.png
https://twitter.com/shiftyeyesmedia/status/877844412465795073
http://chaingame.net/images/up/1634874759_PE3uXF4GiU.png
Thanks!