Swarm is a variant of the arcade shooter Astro Invader. Killer bees are swarming the earth and they are intent on destroying the player's gun base. The queen bee is indestructible and is positioned in the middle of the screen. From there she releases bees which position themselves in columns. Once a column is full the bees begin descending down towards the player who has to shoot at them to prevent them from crashing into him. One difference from Astro Invader is that the enemies here shoot at the player while in the column. When the queen has delivered 100 bees she flies away and returns with a new batch. The player has three lives and when they are all lost the game is over and the queen is able to land.