From Team Fortress Wiki
- steamid (uint64)
- SteamID of user
- appid (uint32)
- AppID to get achievements for
- l (Optional) (string)
- Language to return strings for
- The 64 bit ID of the user
- String containing the game title
- List of achievement objects
- String containing the ID of the achievement.
- Integer to be used as a boolean value indicating whether or not the achievement has been unlocked by the user.
- String containing the localized title of the achievement.
- String containing the localized string or requirements of the achievement.
- Boolean value indicating if the request was successful.