7. Dr. Mario (3DS, Wii, Virtual Console)
Listen, kids: drugs are bad. Unless, in incredibly rare instances, they're being administered by a certified plumber. In that case, they're loads of pill-stacking fun. The Dr. Mario series may be a bit of a niche, even for Nintendo, but that doesn't make its gameplay any less enjoyable or upbeat. The layout of those mischievous viruses forces you to think in vertical and horizontal terms simultaneously, an interesting twist to the familiar falling block puzzler. And despite there being so few colors to match, the action can get hilariously out of hand in a hurry.
We also have a special place in our nostalgia-tinged hearts for Dr. Mario's music: the peppy Fever and spooky Chill themes, which sound incredible in 8-bit, 16-bit, or beyond. And despite being the cause of plague, sickness, and despair, those three rascally virus-gremlins were too adorable not to love.