Use your investigation skills to find and name the hidden rule.
Clues are provided to get you started. IN examples follow the rule. OUT examples don’t.
Test words, letters, symbols, or numbers to gather more clues.
When you think you’ve found the common thread, make a guess. More clues appear when you get a guess wrong, or test a value that doesn’t fit the rule.
You have three guesses to name the thread. You can also spend one guess to get a hint.