On the GoTM シークレットデコーダーアクティビティブック 3冊セット：Slippery Flippers、Runaway Ruby、ゲームブック

My 8-year-old burned through all 18 pages of the Secret Decoder Game Book in one rainy afternoon and immediately asked for more. The magic ink pen reveals the answers, so she actually checks her own work instead of peeking. Wish the pen refills were sold separately.

The red-lens decoder is the real winner here — my son spent a solid hour hunting for hidden messages before dinner. The decoder wheel in the game book kept him busy on a long car ride too. Way better than the usual screen-time battle.

My daughter burned through all three books on a single rainy afternoon and kept going back with the red-lens pages until she'd cracked every hidden message. The decoder wheel is sturdy enough that it survived her little brother grabbing it too, which says a lot.