I like the concept of echo location and have wanted to play around with that concept in a project for a while. The sound fx and music produce a very eerie atmosphere well done. This was a great theme to try this concept! There were a few times I got stuck on the stairs and I lost once under the stairs :). The AI trapped me in a room for a while and I didn't have a stone to get them to leave. After the first three switches I wasn't really sure what to do. I found a green switch but kept getting caught. I saw your comment about the missing checkpoint and I think that would have helped.
Good Job.