There are eight secret achievements in Tron: Evolution for the Xbox 360. I’m not sure why they’re secret though, since they’re unlocked as you progress through the game and not hidden like most secret achievements in other games.
Arjia (20 points) – Completed Chapter Three
End of line (20 points) – Completed the game
Greetings, program! (20 points) – Completed the Tutorial
Identification (20 points) – Completed Chapter Five
Race to the Grid (20 points) – Completed Chapter Four
Reboot (20 points) – Completed Chapter One
Shutdown (20 points) – Completed Chapter Two
The Approach (20 points) – Completed Chapter Six