Humans are the most populous role in Metastasis. In a full game there will be 9 humans all with the goal of defeating the Alien and the Mutant with the help of the Android. This may seem unfair at first, however there is no obvious way to tell whether someone is a human, an Alien or a Mutant unless they transform.
Humans achieve victory when the Alien, the Mutant and all spawns are killed. This occurs even if all humans die in the process, since humanity as a whole has been saved. Humans are not directly penalised for killing other humans or destroying USI property although there may be consequences from angry players or sly aliens implicating you.
Humans are most safe in large groups. Groups of two are extremely dangerous as an evil can easily take a human in a one on one fight, however larger groups massively skew the odds in humanity's favour.
Humans can also confirm their humanity with GIT Testers and a number of edge case items. Modifications to a Human's HP generally do not work on evil or androids, such as Tetrabin, Hormonal Supplements and Government Enhancements.