Dr. Mario games feature a grid that starts out partially filled with viruses of three colors (red, yellow and blue) that Dr. Mario must destroy with pills called Megavitamins of the same color. The game's speed and level can be adjusted before the game, although the speed will increase during a level (but return back to what you chose in the next), and the level of difficulty will increase as you progress.
WarioWare, Inc.: Mega Microgame$ (Game Boy Advance) - 2003 (a virtually full version of Dr. Mario was included as a bonus feature in the game, the only signficant differences being Wario taking Mario's place and limited music selection.