Earth is once again threatened by an alien invasion. The last remaining radio tower is under attack and without it the skilled Sidewinder Commandos won't stand a chance against the invaders. The Sidewinder Commandos is the last remaining helicopter force and the player is one of them. The aliens are programmed to destroy the player so he has to do his uttermost to defeat them.

Sidewinder is a Defender variant. The player takes control of a helicopter and can fly above the planet's surface in any direction. Around him he will find countless of aliens that he has to shoot down or else he will likely meet an early death. The player's objective is to defend a number of radio towers. The player has three lives at start and by every 3000 points he earns a new one. There are a number of different enemies including one that suddenly appears on the screen and then goes right at the player. Before the game the player can choose between ten difficulty levels.
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