I just finished playing Dragon Quest Heroes: Rocket Slime, a Nintendo DS game from Square Enix. It was a blast; neither too long nor too difficult for me. The art is very clean and colorful; the writing is chock-full of atrocious puns (Fort Knight: Not Too Weak!); the controls are simple and well executed.
Rocket Slime is an action-adventure game. Its closest relatives are probably the Zelda series, although it is simpler and sillier than a Zelda. You play a blue slime, out to rescue the rest of your town's slimes from kidnapping by a nefarious mob run by two-tailed platypi.
There are two modes of gameplay. The first consists of bouncing around, bopping enemies, catching them on your head, and depositing them on a train cart bound for town. Once there, they see the errors of their ways and join your cause. You can also scoop up various items and ship them home.
The second mode is tank battles. These tanks are large, multi-story affairs. Your job is to bounce around the interior, bopping enemies and items, catching them on your head, and depositing them in one of the tank's cannons to be fired at the opposing tank. Once you've inflicted enough damage on a tank its mechanical heart is exposed, and you can dash over and give it a good whack to finish the battle. Different items have different effects as ammunition, so there's a small amount of strategy. You can even fire yourself over to the enemy tank; if you make it in you can sabotage it from within.
The items and enemies you collect during your adventures become available for use during the tank battles. Other activities in the game include upgrading the tank, performing alchemy to make valuable items out of lesser ones, and various minigames.
Only a couple of minor things bothered me. The most consistent was the tedious, bog-standard save protocol that afflicts most Japanese games:
"Do you want to save?" (Yes)
"Do you want to overwrite your previous game?" (Yes!)
"OK, I'm saving. Hang on!"
"Do you want to continue playing?"
...all delivered with each letter of dialogue spit out one at a time and no option to skip. All you need is a magic spot on the floor; when you run over it your game is saved. Teach the player how to use it once at the start of the game and you're good to go. The Sly Cooper games have demonstrated that there's no need for the actual saving to interrupt the game at all.
Another minor issue is that the map screen font had me confused for a while about whether I was seeing a 0 or 1 for the number of objectives remaining in an area.
Honestly, though, those are the only things I've got to criticize. It's an extremely well-made game, and I recommend it highly.