Compossbility

From the introduction:

In essence, Compossibility is a stealth/action espionage game. You utilize your abilities, traits, and high-tech equipment to accomplish the goal of preserving the natural course of events. The game begins as you step out of your time machine and into China as it was almost 1500 years ago. Your characters are ignored by the people around them, almost as if they do not exist. They are protected from the attentions of people who are not trained to look for them, as long as they do not do anything rash, like fighting, killing, yelling, jumping around, and so on.