In Polaris, players control a submarine which can only shoot missiles upward. The goal of the player is to destroy all of the planes in each level while avoiding bombs dropped from the aircraft, as well as mines launched by enemy submarines and depth charges dropped from boats that speed by.
- Small airplane: Depending on which level the player is on, there will be six to ten small aircraft in the air when the level begins. One half of the aircraft are pink and move right to left, and the other half are blue and move from left to right. These planes drop bombs (which can be shot at and destroyed), and "loop" (when they reach one side of the screen, they reappear on the other). The small aircraft also move at different speeds according to how many of the same color aircraft have already been destroyed. For example, a pink plane will move slowest when all pink planes are intact, and will move fastest when it is the only one remaining.
- Large airplane: This aircraft appears after all of the small aircraft have been destroyed. Unlike the small aircraft, the large aircraft moves in a complicated pattern, moving all across the sky and performing loops as it drops heat seeking missiles. These missiles drop vertically until they are on the same elevation as the player's submarine, then they move horizontally towards it. These missiles cannot be destroyed. Destroying the large aircraft ends the level.
- Submarine: The enemy submarine periodically shoots an indestructible red mine upward and moves from left to right along the bottom of the screen. Most submarines can be destroyed by moving under then and shooting a missile upward, but in each level there is one submarine which lays close to the ocean floor and cannot be destroyed. In later levels, a smaller white submarine appears which also cannot be destroyed. Like the small planes, the submarine "loops" when it reaches the side of the screen.
- Boat: A yellow boat moves across the surface of the water, alternating from left to right and from right to left. In later levels, there is a shorter period of time between the boat's appearance, up until the time where it appears almost instantaneously after the previous boat has left the screen or has been destroyed. When the boat moves over the player's submarine, it drops depth charges that can be destroyed. When a boat is destroyed, it drops an indestructible mine.
- Small airplane: 50 points
- Bomb: 30 points
- Boat: 100 points
- Bullet: 10 points
- Submarine: 300, 500, 700 or 900 points
- Large airplane: 500, 1000, 1500 or 2000 points
The number of points gained by destroying a pig
Players gain a bonus life at 5000 points. No other bonus lives are awarded.
Every three levels, the player is awarded a bonus. After Level 3, the player gains 1000 points, and each bonus that follows is worth 1000 points more than the previous, until Level 27 is completed, at which point the bonus maxes out at 9000 points.