Monster hunter for 3ds? Pokemon X Y?
Monster Hunter 3G released around the same time as a price cut, Mario Kart and 3D Land.
Pokemon X/Y and Monster Hunter 4 released when 3DS already had 2D Mario, 3D Mario, Mario Kart, Animal Crossing, Luigi's Mansion, Fire Emblem, Kid Icarus, Resident Evil Revelations, Ocarina of Time 3D, Star Fox 64 3D, Nintendogs+Cats, DKC Returns 3D, Dragon Quest VII, Dragon Quest Monsters, Tomadachi, Mario & Luigi, Kingdom Hearts 3D, and a whole bunch more.
There was no single game that suddenly helped 3DS, it was a combination of affordable price plus consistant schedule of quality software.
When the herd loses its way, the shepard must kill the bull that leads them astray.