Achievement

From Styleguide

Achievement

Specific term for special goals that can be completed on Xbox Live-enabled games. Achievement Points are awarded for completing Achievements, which count towards a player’s Gamerscore.

Capitalize names of specific Achievements and put them in quotes. Only capitalize the word Achievement when specifically referring to Xbox Live Achievements; use lowercase when referring to more general achievements in videogames. You’ll need to defeat the Mother Brain, as well as complete various other achievements, in order to finish most Metroid games.

Example: The "Tour Guide" Achievement in Dead Rising only adds 20 Achievement Points to your Gamerscore.

Also see: bonus, unlockable.