Insects from Trifid Nebula attacked Earth, and you should defend the native planet from the invaders.

The game is a platform arcade shooter, where you should control your space craft in top-down view on static levels. During 99 levels the enemies of certain kinds are flying in certain different paths and shooting at you in one direction. The Challenge occurs on each level number divisible by 5. During the challenge indestructible probe with AI helps the programmed flying enemies to defeat you. The Super Challenge occurs on 33, 66, and 99 levels, and it means that enemies of various kinds will fly in certain different paths and will shoot at you.

Killing each enemy will increase your score. When you kill all the enemies on the level, you'll be awarded with the bonus points. If you'll progress in the game without being killed, your space craft will be upgraded as visually as by number of bullets you may shoot at once. 3 levels of your space craft is available.

Finishing the 99th level you'll be transferred to the 1st level again with all your points, upgrades, and lives. When all your lives will be exhausted, you may be enlisted in High Score table based on your scores.

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