Hello,
About the Leap Motion:
I already checked the Leap. It is indeed really good. I tested it into the Oculus, and was very impressed. At one point, the Leap lost track of my hand, and my virtual hand fade out… I really felt my hand tickled, like if my brain was telling me, “whooo dud, your hand is going away”.
But Kinect can provide almost the same thing, and I don’t need to directly look at my hand to see it. What I’ll do is take Leap information for the hand when I have some, otherwise I’ll use Kinect’s information. So the Leap will be the last thing implemented, if the Kinect don’t do the trick.
About giant spiders… well… at one point, just for fun, yes, there will be one. But never in the final app. I promise 
best regards,
Balthazar