I don't know the dimensions off hand, but its a 1800 square foot home and aside from the laundry area (which is small) I am thinking the whole rest of the basement. There is no water damage, and the basement has never had problems with water. The house was built in the 70s or 80s I think.
As far as kids or adults, I am not exactly sure yet, maybe both. I was thinking somewhere where we can have fun, as a family preferably, but maybe also fun for adults as well? I know it can get pricey, but I am just in the thought process now, so I am open to seeing what others have done. I was thinking more in the hundreds or thousands than the 10 thousands or millions if that's helpful.