I followed the matriarch to Peak 15 research base. It turns out, they’ve found a Rachni egg from which a queen hatched. Off course, the Rachni overran the base. After fighting and defeating the matriarch, I got a choice weather to kill the Rachni queen and destroy their race for the second time, or release her hoping that this time they would be different. I chose the latter.
I did a few side quests, one of which led me to the Earth’s moon. It was really awesome to see the Earth rise in the sky. After finishing this quest, I got to choose my class specialization. The choice was either Commando, or Operator. Commando is more on the combat side, while Operator emphasizes Electronics and Decryption skills. I’ve chosen Commando.