Story

You are a lone starfighter pilot battling the evil race of Jalagans, giant bug-like creatures who have been meanacing the peaceful inhabitants of your solar system.

Playing the Game

Each level begins with you warping forward in space.

After you have dropped out of hyperspace, the aliens begin coming onto the screen and taking their place at the top.

Note: Some aliens are only escorts, and will abruptly turn towards the bottom of the screen and attack! After they have left the screen, they will not come back. Try to shoot them for extra points, and definitely watch out not to get killed!

You control your ship by moving it left and right and firing bullets up towards the aliens.

The aliens move side to side (or in other directions) at the top of the screen and occasionally fly down to attack you. They fire bullets down towards you when they're attacking.

Keyboard Controls
The keyboard controls in the game are simple:

[Left Arrow] or [K] - Slide ship left. (Release to stop sliding.)
[Right Arrow] or [L] - Slide ship right. (Release to stop sliding.)
[Space] - Fire a bullet.
[P] - Pause/unpause.

Source
This game is a port of GalaXa from New Breed Software.

The source code is available here.