19. Treasurenauts
Renegade Kid's Mutant Mudds was one of the first unequivocal successes on the eShop. The 3DS title was proof positive that independent developers no longer had any reason to fear Nintendo's digital distribution network. Renegade Kid knew it had a good thing going with Nintendo, which is why it was only natural for the follow-up to come to 3DS as well.
Whereas Mutant Mudds was a bare-bones platformer with a laser focus on perfecting the basic genre mechanics, Treasurenauts sets its sights a little higher. You'll equip any of several weapons and then set out in search of as much booty as you can. There will be massive bosses to battle and secret doors to uncover, but the true Treasurenauts experience is realized with two-player co-op, in which you and a friend use teamwork to reach paths that can't be reached on your own. It's nothing revolutionary, but neither was Mutant Mudds — sometimes it's refreshing to play a game that does a couple of things really well without tripping over itself trying to be innovative or shocking.
Treasurenauts was set to launch this year, but development has been temporarily halted because Renegade Kid director Jools Watsham decided out of nowhere that he had a burning need to make a Metroidvania. That game, called Xeodrifter, will likely hit 3DS eShop before the year is up.