The capsules will be dropping in the playfield. Click the capsule to swap colors. To remove capsules, line up the color and then click on the virus of the same color, drag and click to place the virus to form a complete line. Capsules are removed when the virus is on two or more of the same color going up, down, or in between. Higher points are scored when the virus is placed at a higher height.
As time passes, the level increases. Higher levels mean the delay between capsule drop-ins are shorter and the fall of the capsules are faster.
Do not let the capsules pile up to the top or place a virus at the top row! If just one capsule does not drop in the playing field, the game is over.