In 2014, Earth was invaded by an alien army and most humans were exterminated.
The survivors were enslaved by the aliens. This event became known as the
“Alpha Impact”. In 3693 a human resistance group manages to build a powerful
spaceship capable of traveling through time and sends it to the invasion date,
trying to stop it.

Space Shooter: Alpha Impact (or Impacto Alpha originally) is a casual
space shooter. The player controls a ship equipped with one of two types of
main guns available (selected at the game’s start) and a “super” weapon. The
ship has also a teleport feature which allows the player to quickly evade
approaching threats; it has a power bar which takes a moment to be replenished
after each use. Weapon changes, upgrades, shields and extra lives can be
collected along the game. The player starts with 3 lives and 3 continues.