Some modes have a Wall Type option which can be switched between “normal”, “bouncy”, and “wrap-around”. Wrap-around is the standard and appears in every normal stage of the Story Mode.
The concept of wrap-around mode is simple enough to understand, especially for anyone who has played any of dozens of classic games that use it. Fly through the left side, come out the right. Fly through the bottom, and you’ll see yourself at the top. While flying across an edge, half of your ship will be seen on each side; if flying through a corner, you may even spot your ship in all four corners at once!
This is true of everything else; enemies, bullets, explosions, pick-ups… even your Repulsor will spread through the edges. Enemies are comfortable with wrap around and will fire at the edge of the screen to hit you on the other side. This means that when you’re flying away from an enemy, you’re flying towards them too.
In the Story Mode, the forces of Earth have one trump card that they invented before the World Destroyers even began their attack: the Hyperspace Trap aka Donut Trap. It’s a tactical invention that takes an area of space and “flattens” it into a perfect 2D plane that wraps around in all directions. One scientist made the mistake of trying to explain this as “folding a sphere into a donut, but not really”, and the strategic command has called them Donut Traps ever since.In every normal stage of the Story Mode, your squads are sent into a Donut Trap to clean up the mess it captured. It’s a necessary process as the trap undoes itself after some time, and it’s impossible to blow it all up at once. The trap will delay the World Destroyers' schemes, but it's up to you to stop them.