Just to add - one of the smaller houses in the Alexander has a very small window and one member's hamster got stuck in it, which was traumatic. So the window either needs blocking off (glue a piece of wood over it eg) or that house taking out
I have rarely heard of a hamster that wasn't happy in an Alexander cage - they have the levels as well as the floorspace, a good house, and the shelves give them cover overhead as well.