Atari Anthology Second dimension shooting in Asteroids
You must be at the side top or bottom of the screen. Then, shoot towards that part of the screen. Watch the opposite screen to see your shots come through. Note: This works best when a asteroid is on the opposite side, as you will have a chance of exploding it.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art / Original