Target Earth (Assault Suits Leynos or Jūsō Kihei Reinosu; 重装機兵レイノス in Japan) is a video game developed by NCS Corp in 1990 for the Sega Genesis and the Sega Mega Drive. It has since been re-released on the Wii as a Virtual Console product in Japan. Target Earth is the English translation of the original Japanese version, Assault Suit Leynos. While the official information for the game indicates that it is only single player, it is possible to have two players opposing each other by using two controllers.
It is the year 2201 and expanding technologies have given man the power to live anywhere in space. Amidst this backdrop, the story of Target Earth begins with a war between Earth (and its colonies) against a cyborg army returning from the farthest reaches of space. In the game's early stages, the nature or purpose of these cybernetic adversaries, named Chron, is unknown. However, it is later revealed that Chron are the survivors of a failed space expedition (Outer Space Expeditionary Party) sent by Earth a hundred years earlier.
The Earth Defense League fights to defend Earth. The heart of the defensive movement is the Assault Suit-- a twelve-foot tall armored battle machine with awesome fighting capabilities. You are Rex, an Assault Suit Wing commander and master at Assault Suit combat. The battle begins on Ganymede but shifts to battles in space, on the Earth, and inside enemy outposts.
Target Earth is memorable for its well-developed storyline (particularly for an action shooter), catchy music, impressive parallax effects for its time, reward mechanics, and legendary difficulty.
Source: Wikipedia, "Target Earth (video game)", available under the CC-BY-SA License.