Level 1 will only have ONE thing in common. Your first guess is usually accurate.
Level 2 will be a bit more complex. All the words will have TWO things in common.
Level 3 will be the most difficult. All the words will have THREE things in common.
Level 4 will be the date of a famous event in world history.
Level 5 will be the title of a book, poem, song, fable, etc.

 

Level 5

Thank you Jen Wagner