They just sold their last copy a few days ago. Waiting on a restock...
I had added this to an order when it was in stock that should have shipped out yesterday when another item the order was waiting on finally became released. When my order didn't ship and still wasn't processing this morning I sent a message and they said my order was waiting on Celestia.
I knew I wasn't crazy and that Celestia had been in stock when I added it to my order so I questioned this and someone else got back to me and explained that Celestia had gone back to pre-order status but that my copy should be set aside for me so my order should ship today.
I think that this game going from in stock back to pre-order caused my order to remain on hold even though my copy was there.
I can't say I've seen a game go from in stock back to pre-order. It normally is just out of stock until a restock. Not sure why they are going back to pre-order status on this one.