Earth Defense (aka: The Earth Defend) is an unlicensed game for the Sega Mega Drive/Genesis; it was developed by AV Artisan and published by Realtec in both North America and Taiwan, without a license from Sega.

In Earth Defense, aliens have invaded Earth. In response, the United Nations create a flying craft named the "Phoenix Spitfire" to fight back and defend the planet, with the player in control.

The player will fly through five vertically-scrolling levels while shooting down enemy craft, confronting a boss at the end of each level. The Phoenix Spitfire is equipped with a standard cannon that can be upgraded by finding power-ups throughout the levels, left behind by defeated enemies. Upgrades to the cannon include the Tri-Shot, Napalm Bomb, Rear Shots, and support drones.

Description from MobyGames