Had some fun with this.  

I really liked the mix of sight and audio puzzles. I found I spent most of the time using the sound mode which seemed better for most of the puzzles though. Maybe it was because I lost all vision of areas I had already visited if I didn't have direct line of sight. Obviously you shouldn't see the enemies without LOS but still being able to see the layout could help make it more useful.

One thing I would like to see is some sort of lure or distraction to force guards to move. This could open up some additional puzzle options.

UI and sound was great it felt super polished. Nice work!