Platform: NES/Famicom
Released: 1990
Developer: Nintendo R&D1
Genre: Puzzle Game
You're probably familiar with this one, considering this series is still around today. The original Dr. Mario was a fun puzzle game, and the first one to feature Mario. The goal of the game is to annihilate the viruses by matching pills of the same color close to them. The game starts off easy with just a few viruses and would become harder as you progress, giving you more viruses to defeat. An important aspect of the game is that you need to rotate the pills; some pills have different colors on each side.
The game also had a two player mode in which the two would compete to see who could destroy the viruses faster. This game launched the Dr. Mario series, although we wouldn't see a true sequel until Dr. Mario 64 (2001). Most recently, Dr. Mario: Miracle Cure was released for the Nintendo 3DS eShop. And Dr. Mario is also one of the fighters in Super Smash Bros. for 3DS and Wii U. It all started with this humble puzzle game.
I need some medicinal Mariojuana 
I see what you did there. This might be the only Nintendo game where they advocate drugs! But of course, the doctor giving them is Mario, so it's all good.
Dr. Mario was sued several times ... or so they say. Something about mushrooms on the job.
Don't forget Dr. Luigi. :)
Dr. Mario is one of my mom's favorite games.
The viruses were also enemies you can beat in one of the Mario & Luigi games.
Ah yes, Dr. Luigi, the strange spin-off they did for the year of Luigi. I should get that bc I love Luigi!
Dr. Luigi's also on Dr. Mario: Miracle Cure.
I'm no good at Dr. Mario. My wife is great at it.
Well, I'm not too hot at puzzle games either, but we all have our own strengths and weaknesses.
I have Dr. Mario on my 3DS. I like it.
It's a good game. Maybe I'll play it again for ol' time's sake.