The Varginha Incident (also known as Incidente em Varginha, Alien Anarchy, or Alien Shootout) was developed by Perceptum Informática and released in 1998. It uses the Acknex Game Engine (now known as Conitec 3D Gamestudio).
The game is based on a much-publicized and allegedly true series of UFO sightings said to have happened in January 1996, in the city of Varginha, Brazil.
Varginha, state of Minas Gerais, southeast region of Brazil. January 20th, 1996. Extraterrestrial visitors were captured by the military. As a witness of the incident, they want to get you too. You must fight the military, liberate the aliens, and retrieve their spaceship.