For me, all you did was good enough.
From the get-go, I will say straight: this would make freaking amazing game music. For a puzzle game or something, this would be completely unreal. I love the melody and lead and echo, but the only thing I would recommend is that something be done about the snare. It's a little out of proportion in volume to me. You may have just wanted it to stand out, and that's good, but maybe something else in place of that...? Maybe a different snare, one that blends a bit better with the whole ambient theme...? Other than that, the song was amazing; I felt like I was being thrown in a chasm or a void.