Kill 3 enemies in a single turn, with a single soldier, without explosives

Build the Shadow Chamber

Kill a Berserker in melee combat

Kill 500 aliens. (does not have to be in same game)

Skulljack an ADVENT Officer

Find 1 Treasure

Beat a Retaliation mission with 3 or less civilian deaths

Upgrade a facility

Apply a PCS upgrade to a soldier

Cause an enemy to die in a car explosion

Make contact with a region

Complete a successful ambush

Kill a Sectoid who is currently mind controlling a squadmate