This singular power is maintained by a strong and special magnetic ion held in their bodies, thus making them susceptible to a variety of cosmic rays which exist in nature, this being their reason for taking residence in the southern hemisphere, where the incidence of cosmic rays is relatively low. The psychic power possessed by a Wreek was known as Wreek Power and was known to be usable as an energy source for all kinds of powered equipment and living bodies.

Although their lifestyle was primitive, they possessed psychic powers which allowed them to communicate telepathically with other tribes. The Wreek was the only ethnic group living in the southern hemisphere of Planet Gradius.

The Empire's major operations are focused on the northern hemisphere where the sun is shining while little development of the southern hemisphere has been done. The Gradius Empire, with its planet as its mother star, has a population of about 2 billion people, and colony stars called seven neo-space plants on its vicinity. For this reason, the northern hemisphere benefits from the sun the entire year and conversely the southern hemisphere has been closed to darkness. The Planet Gradius is located at a distance of 280,000 km from its sun and its axis is kept substantially horizontal to the sun. But, who could foresee that slight damage to the Southern Hemisphere closed to the darkness would later become a trigger to lead the Gradius empire to crisis? In this fight the damage the Gradius Empire suffered ranged to 65% of the planet as a whole, most of it concentrated in a certain imperial city on the northern hemisphere.

Some predetermined enemies will not appear if the screen is already occupied by too many other enemies.Gradius Calendar 6644, the First Planetary War, which broke out with the Bacterian Subspace, is described as ' Northern Cross Battle' in Gradius's history.

The reuse of this sprite from Life Force cosmetically alters the Vic Viper from a single thruster engine to a pair of engines. Player 1 uses Vic Viper's coloration of a blue ship with red options, while Player 2 uses the Lord British coloration red with blue options.

Similar to Life Force, each player is represented by slightly different colors.

After completing the final stage and returning to the first stage, the difficulty increases, but it will not increase again on subsequent completions.

Bosses can never be defeated by waiting long enough until they self-destruct.

The hit box which surrounds the Vic Viper is a bit larger in this version, making it more vulnerable to attacks.

The Option Hunter does not appear in this version.

This feature imitates the time limited Rotating Barrier power-up which originated in Gradius 2 for the MSX. For a limited period of time, all four Options will rotate around the Vic Viper before returning to the traditional snake-follow pattern, at which time Option will reappear on the power meter and can be activated again.

After you have activated four Options, you may choose the Option command again to activate the Option Rotation behavior.

As a result, it is capable of sustaining five hits before depleting, as opposed to three in the arcade version.

You can no longer choose between the Shields and the Force Field.

Both the Laser and the Ripple can be selected twice, once to activate it, and a second time to improve its effectiveness.

Both Laser abilities produce the Cyclone Laser effect, which is generated by rapidly drawing different chunks of the laser on every frame.

Rather, a small circle indicated the position of the bomb, and the explosion it produces is much more effective at eliminating enemies than in the arcade game.

The Spread Bomb ability does not actually produce missiles like the other Missile abilities do.

The vocalization of Gofer is also accomplished through combinations of these words.

They are simplified and the same for all four power type arrangements, but they are present. It is also the only Famicom conversion of a Gradius game to feature the vocal announcements of activated power-ups.( Gradius allowed two, and the Japanese version of Life Force allowed for three Options, shared between both players.) It is noteworthy that as the last Famicom conversion in the series, Gradius II finally allows players to activate four Options just like in the arcade.

Gradius 2 nes levels