My kids got a really cute cardboard indoor playhouse for Christmas from their aunt. Â I finally set it up yesterday, and they spent the rest of the day playing in it. Â It's pretty big and made from cardboard. Â It's meant to be colored on with markers.
I listed photos and a video of them playing in it here: Â Kids Indoor Playhouse
These type of cardboard playhouses come in some other really cool designs like a cardboard pirate ship, or a cardboard castle playhouse.