Here is the full list of all 11 UNDETECTED achievements.
Find the Chicxulub Power Station
Discover what happened to Gloria
Hack the mainframe
Encounter Jimmy McCoy
Encounter Evelyn Johnson
Encounter Agent C-4815
Encounter Hunter Patton
Finish the game
Break a wall to save a carnal
The Chameleon must be destroyed
Finish the game in Mexican Extreme difficulty