Sky Destroyer is an aerial combat game. Players take the role of a warplane that has to defeat various enemy combatants in the air and in the sea. The player's warplane is equipped with machine guns and can also fire off torpedoes. The main goal is to destroy a fortified island at the end of each scene by firing a torpedo at it.
Gameplay is viewed from a behind the plane viewpoint. While flying. players will notice time elapses by the background changing from day to night and then back to day again. The is to help indicate to the player that they are making progress throughout the level. When the player cycles to the next daytime sequence, the player will be able to know a island should be coming up soon. After taking out the fortified island, players will get a chance to play a bonus stage where the objective is for the player to destroy as many planes of an incoming enemy fleet as possible, with each destroyed plane adding to the player's score. Managing to destroy every single plane in this bonus round will also give the player additional bonus points to add to their overall score.
The player starts with three lives and can lose them by either getting hit by incoming enemy fire or crashing into the water that is below them.