Virus Attack! was an online Adobe Flash game developed and published by Nintendo as part of the yearly Camp Hyrule event, which was hosted 13 times from 1995 to 2007. It is unknown what year or years the game was available to be played.
The game is similar to Space Invaders or Galaga, featuring a spaceship with 3 lives controlled by the player. The left and right arrow keys move the ship in the respective direction, and the up arrow key makes the ship shoot. The screen above the ship is filled with a grid of Viruses from the Dr. Mario series. The player's goal is to shoot the viruses until there are none left. There are three levels that have to be played before the game is complete. Each new level makes the game slightly harder by adding an additional row of viruses for the player to defeat. The first level has 4 rows, the second level has 5, and the third and final level has 6 rows. Occasionally, a virus will come out of its row and charge at the player, but if it misses, then it will go past the bottom of the screen, reappear at the top, and go back to its row, similarly to the enemies in Galaga. Each row of viruses is worth a different amount of points, with the first row being worth 100 points, the second row being worth 200 points, and so on. Once the game is beaten, a screen pops up saying that the player saved Camp Hyrule, and found the "pulse oscillator". If the player runs out of lives at any point, then the game displays the message "Game Over" and returns the player to the title screen.