Steam Community :: Screenshot :: Underground map. "clear" slanted square marker -- my term for it :-) -- means you activated Module there. If it's purple color, you haven't.
Hyper Light Drifter review | Eurogamer.net
Hyper Light Drifter: A Perfect Immortal Cell. – The Refined Geek
Land of Light | Hyper Light Drifter Wiki | Fandom
Drifter: The HLD Tabletop Role-Playing Game on Twitter: "Take a sneak-peek into the expanded world of Hyper Light Drifter, just a piece of the greater continent that you'll be able to traverse