Keep in mind that we don't have kids . . .

I might be able to rationally justify this purchase to people . . . if one of its main purposes wasn't to figure out if the kittens would be interested in an even larger (and thus more expensive) one.

Loki on his way up

Zoey making sure she wasn't missing out on any of the fun Loki was having above

"I know you're in there, Zoey"

Hanging out

Zoey being cute

You can see how there's a hole in the top level that let's them climb up and through. It is completely enclosed where Zoey is.