A great game, but holy hell, does it make you feel like shit.
Visual novels tend to leave me feeling a bit lacking in control over the character's actions - well, Echo does a great job of letting you feel like you have control, only to show you that your actions were ultimately meaningless, and you could do jack shit to stop all the horrible things that happened.
The genius however, lies in HOW it does it - not the "the plot demands it" way, rather the "you were just a part of something much bigger" way. As the plot moves forward, it builds the feeling of helplessness and dread, giving you only short moments to catch your breath.
The cast is also fleshed out and, for lack of a better word, believable - which only makes it easier to get attached to the characters, only for your feelings to get brutally mangled. I thoroughly recommend it, but DO NOT play if you're in a fragile mental state - "Echo" left me feeling hollow and broken after just one route, and I don't expect the rest to be any less haunting.