A real-time puzzle game, reminiscent of Pipe Dream 's basic idea crossed with a sliding-block puzzle. The goal is to form a continuous pipeline, conducting the flow of a red liquid from source to destination. Each level starts with a grid of jumbled pieces; the player is represented by a movable tile, which can slide in four directions, exchanging places with adjacent tiles. Non-player tiles are either blank or occupied by a pipe section: a horizontal or vertical straight line, a corner, or a cross-shaped piece (which allows both horizontal and vertical flow). The liquid starts flowing as soon as the level begins, and the pieces must be re-arranged in real time to carry it safely from start to finish. Pieces can no longer be moved if they contain liquid; the round is lost if the liquid reaches a gap, or tries to flow into an ill-fitting pipe section. Up to two human players may play simultaneously, using the keyboard. Pipeline features fifty levels of increasing difficulty, which can be played in no particular order - some levels add a computer-controlled third "player" which moves about at random, frequently blocking your movement and destroying your carefully-constructed plumbing.