In keeping with the technical limitations of the device, the game features a playfield measuring eight-blocks by 15-blocks and viruses of black, white, and gray. The Game Boy version of the game is nearly identical to its NES counterpart. Much like Tetris, the player may choose a level of difficulty to start, along with the game's speed and a selection of background music. Levels do not increase in difficulty past level 20. Above level 20, each level starts with 84 viruses. The game consists of 21 distinct levels, whose starting virus counts range from four at level 0 to 84 at levels 20 and higher. Conversely, the game will end if any capsules obstruct the bottle's narrow neck at the top row of the field. A player completes a level by eliminating all viruses on the playing field. Both viruses and capsules are eliminated when four or more objects of corresponding color are placed in a row or column. The player must rotate and position these capsules on top of and alongside the viruses and other capsules in an effort to eliminate the viruses.
There are six types of capsules, differentiated by their color: red-red, yellow-yellow, blue-blue, red-blue, red-yellow, and blue-yellow.
Play consists of dropping two-sided vitamin capsules into an eight-block-by-16-block playing field populated by viruses of three colors (red, yellow, and blue).
Mario features Nintendo mascot Mario as a doctor.
