When XCOM removed the biochip of a living Viper, they unintentionally gave her something else: Freedom. No longer a brainwashed servant of the Elders, Natasatch asked to join XCOM, much to the project's surprise. However, the prospect of integrating an alien into such an anti-alien organization may just be XCOM's most ambitious experiment yet.

With the Vipers now openly rebelling against Advent, XCOM's fight against Advent seems to have gained momentum. However, as new shadows rise to break the will of the resistance, the Commander himself now finds it difficult to maintain his high confidence and will. With a growing sense of self doubt, can the Commander fight not only Advent, but also to keep his humanity?

X-COM 2: Project Sigma is an adult Viper fanfiction, based on X-COM 2. It's got sexy snake boobs, which is a perverted and shameful thing that you probably shouldn't read (but you will anyway). But its also got hard science—both real and speculative—and serious plot. If anyone finds the science getting in the way of enjoying the snek tits, I offer my deepest apologies.