Castle Blaster 2D is a side-scrolling shooter that places the player at the controls of a spaceship, armed with a powerful blaster. The goal is to navigate through a maze of treacherous tunnels while destroying enemy spaceships and avoiding obstacles.
The player's ship can move left and right along the horizontal axis, and a single blaster shot can be fired at a time. The blaster's ammunition is limited, and finding power-ups scattered throughout the levels can replenish it. The player must also contend with enemy projectiles that can damage the ship rapidly.
The objective is to clear each level by reaching the exit portal at the end. As the player progresses through the levels, the difficulty increases with more aggressive enemy behavior. The game can be played in a browser without the need to download or register, allowing for easy access to the gameplay experience.