Xavier - 25 gamerpoints - Mind Control an Ethereal. Single player only.
Meet New People. Then Kill Them. - 10 gamerpoints - Win a multiplayer match.
Angel of Death - 10 gamerpoints - Kill an alien while flying. Single player only.
Beyond the Veil - 10 gamerpoints - Find a soldier with the Gift.
Prisoner of War - 10 gamerpoints - Capture a live alien.
The Gatekeeper - 10 gamerpoints - Stun an Outsider.
X Marks the Spot - 10 gamerpoints - Uncover the alien base's location.
See All, Know All - 10 gamerpoints - Build the Hyperwave Relay.
On the Shoulders of Giants - 10 gamerpoints - Build the Gollop Chamber.
Ride the Lightning - 10 gamerpoints - Build a Firestorm.
Poison Control - 10 gamerpoints - Cure poison on five soldiers in a single mission. Single player only.
And Hell's Coming With Me - 10 gamerpoints - Successfully assault an Overseer UFO.
Off My Planet - 25 gamerpoints - Recover the Hyperwave Beacon.
The Volunteer - 10 gamerpoints - Make contact with the Ethereal hive mind.
Flight of the Valkyries - 10 gamerpoints - Win a mission with an all-female squad. Single player only.