Going back at least to the PlayStation vs. Nintendo 64 days, Nintendo has had a reputation for targeting their games and consoles at kids and families. There’s certainly nothing wrong with this strategy, but its effect has been greatly overstated. The GameCube, after all, was the original home of “Resident Evil 4,” and titles like “Eternal Darkness: Sanity’s Requiem” and “Beyond Good & Evil” surely weren’t made with children in mind.

But, like it or not, the stereotype continues to hang around, and with the Wii’s biggest hits being titles like “Guitar Hero: World Tour,” “Rock Band 2,” “Super Mario Galaxy,” “Wii Fit” and “Wii Sports,” it’s starting to gain a little more traction. For better or worse, the hit, M-rated games ” the “BioShocks” and “Grand Theft Auto IVs” of the world ” continue to get made for the Xbox 360 and PlayStation 3, but not Nintendo’s machine.

You can chalk this trend up a bit to the Wii’s lack of processing power when compared to its rivals, but that explanation only goes so far. The Wii has outsold both its competitors by millions of units. Clearly, if game publishers thought there was money to be made in mature titles on the Wii, they’d be releasing more of them. An early experiment, Rockstar Games’ “Manhunt 2,” flopped, although that might be at least partly because of its poor reviews.

Still, the trend for more adult-oriented titles on the Wii, as well as Nintendo’s DS handheld, took a hit late last week with the NPD Group’s release of its monthly report estimating U.S. video game sales.

First off, “MadWorld” (rated M, $50), an ultraviolent title whose art direction is reminiscent of the “Sin City” graphic novels and film, sold just 66,000 copies in the U.S. in March, following its release on the 10th of that month. (Generally, anything less than a few hundred thousand copies is considered a flop, with a million in sales being considered a blockbuster or hit.) The game may have had an uphill climb, though, as a brand new franchise on a console whose audience probably doesn’t pay as much attention to new releases as Xbox 360, PC or PS3 gamers.

More surprising, however, is the flop of “Grand Theft Auto: Chinatown Wars” (rated M, $35), which sold just 89,000 copies for the month, fewer than half the number of units the stingiest prediction thought the game would move. “Chinatown Wars” has all the makings of a hit. It’s a wholly new adventure from a proven franchise, being released on the world’s most popular handheld. A trip over to Metacritic, which aggregates game reviews the same way Rotten Tomatoes does for films, shows it’s the best-reviewed game for the DS, with an average score of 94 out of 100. Seth Schiesel’s review in the New York Times summed it up aptly, while also illustrating why the game shouldn’t be bought for kids.

It’s hard to know, exactly, why folks didn’t snap up a pair of well-reviewed, M-rated titles for Nintendo machines, and the games’ failure to sell by no means should indicate that publishers are done releasing adult-oriented titles for the Wii and the DS. But if you’re an owner of one of those two machines, and you’d like to see more mature games than minigame compilations on the Wii or puzzle games and pet-raising simulations on the DS, give “Chinatown Wars” and “MadWorld” a look.