Dr. Mario (Classic NES)

In Dr. Mario players compete in puzzle challenges, trying to create chains of four same-colored pills and viruses, with the ultimate goal of getting rid of all viruses on screen. Left-over pieces fall downwards, thus enabling multi-link combos. Once all the viruses have been cleared, players move on to the next stage -- featuring more viruses and faster pieces. Needless to say, the gameplay can get rather frantic in a hurry, especially in the series' staple multiplayer modes.