Astro Barrier

Astro Barrier was a Club Penguin Online minigame located in the Arcade, next to Thin Ice and resembled a retro arcade shooter.

Gameplay
The goal of the game was to successfully hit all targets on the screen without running out of shots.

Press the left and right arrow keys to move your ship. Pressing the space bar will make the ship shoot, but shots are limited (from 3 to 8). More ammunition is given as the game progresses.

Secrets

 * It was possible to skip levels right after clicking start. On your keyboard press 1 to go to level 10, 2 to go to level 20, or 3 to go to level 30.
 * The secret levels in Astro Barrier were accessible before level 11 starts. Wait 30 seconds when the screen is showing information about the orange switch, and shoot the blue ship that appears. Then after the 10 Secret Levels, you will skip levels 10 to level 16.
 * The Expert Levels were accessible before level 31. Wait 25 seconds and shoot to make the turret shoot the blue ship. Then after the 10 Expert Secret Levels, you can shoot five targets with a number of 500. That means you got 2500 extra points. Then the game is won.
 * You could earn more points to addition to your coins by shooting at targets and blasters when they are in the Instruction Pages.
 * Before proceeding on to another level, a loading box will appear for about 4 seconds. This box isn't a real loading box. But if you press enter, it will disappear and you will progress to the next level.

Trivia

 * The Secret levels were the shape of the numbers. The shape of the level would vary depending of the level you were playing except level 10, where the number is 0.
 * The ships (both the white one and the blue one) resembled the Snowspeeder from Star Wars.
 * This game was designed to be an 8-bit game.
 * It was featured on the Astro-Barrier Card-Jitsu Card.
 * It was likely based on real-life games Galaga and Space Invaders.

Targets
There were several types of targets introduced throughout the game, with new ones having new properties and rewarding the player with a different amount of points:

Stamps

 * See main article: Astro Barrier Stamps