We play this with our kids on car rides with some regularity. We usually limit scope to some book series- LOTR, Harry Potter, Star Wars, etc. Kids get really a

We play this with our kids on car rides with some regularity. We usually limit scope to some book series- LOTR, Harry Potter, Star Wars, etc. Kids get really annoyed when I pick something super obscure like “a hair on Gandalf’s beard”. So I do. But they know it’s my strategy so can often guess anyway. If you know the owner skews towards obscure you can weight the binary search towards obscure.