Just finished up Hyper Light Drifter. It's like 16bit Zelda on a bad acid trip. Part of the game itself is figuring everything out without tutorials, dialogue, or story explanations. A lot of hidden things to find. Maybe the worst soccer minigame I've ever played but overall it feels like a top tier SNES title.
To find the location of that boss, you have to look for stonehenge-like monolith formations. It took me days of sailing around to find one but I spotted it off the coast and sure enough, it was the right thing. Try to sail and look for it as much as possible without getting off and fighting those deathsquitos and stuff.