Hive: The Pillbug is a new pair of tiles that can be added to Hive. The pillbug moves like the queen bee—one space at a time—but it also has a special ability that it may use instead of moving. This ability allows the pillbug to move an adjacent unstacked piece (whether friendly or enemy) two spaces: up onto the pillbug itself, then down into another empty space adjacent to itself. Some exceptions for this ability:
- The Pillbug may not move the piece most recently moved by the opponent.
- The Pillbug may not move any piece in a stack of pieces.
- The Pillbug may not move a piece if it splits the hive (violating the One Hive Rule).
- The Pillbug may not move a piece through a too-narrow gap of stacked pieces (violating the Freedom to Move Rule).
- Any piece moved by the Pillbug may not be moved at all (directly or via the Pillbug action) on the next player's turn.
The mosquito can mimic either the movement or special ability of the Pillbug, even when the Pillbug it is touching has been rendered immobile by another pillbug.
The expansion consists of two game pieces (one each for the black and for the white player), to be used in addition to the pieces of the base game.