Zero Tolerance

The game takes place in a future where mankind has made great advances in interstellar travel and subsequently colonized the Solar System. There are extrasolar settlements, research outposts, mines, commercial colonies, and spacecraft and space stations throughout the Solar System protected by an interstellar military conglomerate named the Planet Defense Corps.

When Europa-1, the flagship of the Planet Defense Corps, is attacked by an unknown yet lethal aggressor of extraterrestrial nature, the Planet Defense Corps call in Zero Tolerance, an elite strike squad containing five specialty-trained commandos. A recording of Europa-1's last transmission shows that there was a lot of fire damage to the warship, that almost everyone on board died, and that strange creatures were looking for the few people who managed to escape the attack. Additionally, the nuclear cooling system of Europa-1 has been damaged by a small arms fire, and a core breach caused by overheating will destroy the starship in a matter of hours.

During the crisis briefing, the player character is told to sneak into Europa-1 before it blows up as a member of the Zero Tolerance squad. Their mission is to eliminate the mysterious alien aggressor from within and the transformed humans of Europa-1 that have been "infected" in the next few hours to erase all evidence of the attack and the alien intruders.