The answer to the riddle is hidden somewhere in the grid of letters. Find every letter of it to win.
Tap any letter A-Z in the keyboard above the grid. If it's in the answer, the grid lights up white wherever that letter appears. If it isn't, the key fades instead. Then search the grid and tap the letters that spell out the answer. Correct taps turn green; wrong taps fade. The riddle is solved when every letter in the answer is selected and turns green. You lose a point for every wrong pick and every hint you use. The lower your score, the better.
Here's what that looks like partway through a riddle:
Once you solve it, tap SHARE to challenge a friend to beat your score - on a computer this copies a challenge message to your clipboard instead of opening a share menu.