[ContainerTed]

My first thought is a "French Drain" running from the yard drain as far as you want back toward the Playhouse or even beyond. This would keep the area much drier overall and your choices of what to put down for the walkway increases. I would put down larger flat/flag stones set into the surface area above the French Drain. The picture you referenced in your first link above would be very possible. If there is water coming from more than one source, branches off the French Drain would make it easy to capture this additional water intrusion.