Definitely a very unique entry and a cool idea for interpreting the theme, and I guess technically a Metroidvania in the most fundamental sense. (Does every item that gives access to a new area in a video game automatically make it a Metroidvania? I don’t really want to get into the philosophy of it, but I suppose it’s really up to individual interpretation!) Sadly, being pretty bad at point and click games, I wasn’t able to get very far (only as far as wandering about in the technical section, based on the maps in the extra folder), so take my feedback with a grain of salt!
I do appreciate the dedication to black and white graphics, and some of the sprite work is pretty nice (once you’re able to see it). However, I don’t think it interacts with the echolocation mechanic very well. Since black is the color of both areas that haven’t been echolocated yet and areas that simply have nothing of interest in them, it’s often not immediately clear if you’ve even successfully used echolocation or not. The cooldown also doesn’t exactly help here, and I think having a cooldown on what is essentially your ability to experience the game is just too punishing.
Even though it’d mean breaking with the duotone artstyle, I think having a third color for walls (basically areas that have been revealed but don’t have anything in them) would be a massive improvement. That way, at least you’d be able to keep track of what you’ve already looked at, and what could still contain useful items. Also, the inventory was hard to see over white objects due to having no background, so another color (or even just putting a black square behind it) could help there too.
With all that said, I think the game does a great job at capturing the oppressive atmosphere of the regime, and the subtle ambience makes it even creepier. The idea has a lot of potential too, and doesn’t have to be limited to point and click games either - but I think it definitely needs some work to make sure it works for the player rather than against them. I’m pretty sure there have been several games with this kind of echolocation mechanic, so perhaps looking at them for inspiration could help!