Virus Wars is a two-player board game that simulates an evolution of two colonies of viruses, which are growing and absorbing (zombifying) each other.
The exact origin of the game is unknown but it was actively played as a paper-and-pencil game in Saint Petersburg State University in 80s.

The goal of the game is to leave the opponent without legal moves.

Starting with Blue, players take turns making 3 steps per turn.
Each step can be either generation or absorption:

• Generation includes putting a new virus of player's color on any "accessible" empty square of the board;
• Absorption includes zombifying one of opponent's viruses on any "accessible" square of the board, i.e. replacing an opponent's virus with a special "zombie" piece of player's color. "Zombies" remain permanent till the end of the game, i.e. they cannot be "revived", "reclaimed" or removed from the board.

A square is "accessible" in the following cases:

• The "square" is vertically, horizontally or diagonally adjacent to a player's virus already on the board (even if that virus was placed as one of the previous steps during the same turn);
• The "square" is connected to a player's virus already on the board through a chain of horizontally, vertically or diagonally connected "zombies" of player's color (even if those "zombies" appeared as one of the previous steps during the same turn).

See Also: http://www.iggamecenter.com/info/en/viruswars.html
Video: http://www.youtube.com/watch?v=4GGJKV_NtRg