Number Hunt

Beyond Learning, $20

What makes this educational board game stand out is its adaptability. With six different sets of rules, each pegged to a different mathematical skill level, Number Hunt can have value for kids just learning to count as well as those ready for more abstract addition and subtraction. As they race from leaf to leaf along a winding green vine, younger players can engage in simple counting exercises; more advanced learners can instead compare the value on the die to the number of bugs on their leaves. The most challenging level even enters a quasi-algebraic realm. The multiple stages of difficulty will encourage kids to keep pushing themselves. —Ages 3 to 6

Beautiful Katamari

Namco Bandai, for Xbox 360, $40

In one of the strangest of video-game plots, the mite-size Prince of All Cosmos attempts to impress his giant, capricious father by rolling up big balls of, well, stuff. But this bizarre storyline is, frankly, peripheral to the original, fun, and utterly addictive gameplay. The prince is armed with a katamari, a magnetic ball that attracts anything smaller than it. As the sphere is rolled across a household floor, picking up tiny items like pushpins and crackers, its mass increases, and soon it's capable of scooping books, pets, chairs, even people. Eventually, a gargantuan katamari will hit the open roads, rolling up trucks and buildings. Hidden among the surreal chaos is a lesson in comparative mass and volume. —Ages 6 and up

Dewy's Adventure

Konami, for Nintendo Wii, $50

In order to save a mythical life-giving tree from an army of anthropomorphic pollutants, players take control of the most unlikely of heroes—a drop of water. By simply tilting the Wii's motion-sensitive remote in various directions, you guide "Dewy" through mazes and past enemies. In a truly ingenious twist, you also control the temperature in the Land of Eau—and with it, Dewy's physical state. Make it hotter and Dewy turns into a mist, capable of floating over obstacles. Or bring the mercury down to solidify an ice version of Dewy that can slide faster and freeze foes. The fantasy, action, and science all mingle remarkably well.—Ages 5 and up

Nancy Drew: Legend of the Crystal Skull

Her Interactive, for PC, $20

Oh, Nancy Drew. Did you really think your visit to the New Orleans mansion of a friend whose rich uncle just died mysteriously would turn out to be nothing more than a fun Big Easy vacation? Within moments of Nancy's arrival, everyone's favorite amateur detective becomes embroiled in a mystery involving a contested inheritance and an ominous stranger in a skeleton costume. And you control her every move as she scours dark corners of the eerie estate for clues, interrogates creepy suspects, and calls upon her best friend, Bess, for occasional assistance. The 17th entry in the popular PC game series is rife with secret passages and hidden codes—so getting to the bottom of it all requires a serious brain workout.—Ages 10 and up

Ben 10: Protector of Earth

D3 Publishers, for PlayStation 2, PlayStation Portable, Wii, and Nintendo DS, about $30

Just as he does regularly in his hit Cartoon Network series, prepubescent hero Ben must save the world from an extraterrestrial invasion. The action is fast and furious, requiring quick reflexes and even quicker thinking. With his unique superpower, Ben can transform into any of 10 different alien superheroes (hence the name), each of which has its own special skills. As challenges present themselves in the game, players must decide which of Ben's personae will best fit the situation.—Ages 6 and up

Fishing Master

Hudson Entertainment, for Nintendo Wii, $40

Stand up and get ready for some exercise. After whipping your arm overhead to cast the line, rotating your hand to reel in your catch, and tugging the pole (that is, your Wii remote) back and forth to keep that giant sea bass from getting away, you'll realize what a physically demanding sport fishing can be. In this take-it-at-your-own-pace game, you'll hit dozens of fishing spots all over Japan, exploring salt water and fresh, deciding which types of bait and lures to use, and hauling in more than 100 breeds of fish, from trout and minnows to eels and blowfish. Up to four players can compete for the biggest catch.—Ages 5 and up