It's a video game where the main character you control is playing a video game.
You play a dude named Desmond in the 21st century. There are magic chairs that allow him to revisit his ancestors' memories through genes and stuff. One of his ancestors is the middle eastern dude from the first game, another is the Italian dude from the 2nd, and another is this native american in the 3rd game. There's a lot of other spoilery stuff when you get down to it, but you're not time traveling.