Unique idea, though I did find one or two of the sounds to be a bit misleading (thought the rolling boulder was thunder). There's also a lot of waiting in this game, which if shortened would make the gameplay feel tighter.
I got as far as the arrows level but the horse ended up staying in place in front of the archers, don't know if that was the end or a bug. I like the concept though, and got a good enough feel for it by that point.