Here is the full list of all 12 Warhammer 40,000: Sanctus Reach achievements.
Kill 25 units with flame attacks
Kill 100 Space Wolves
Kill 100 Astra Militarum
Kill a Morkanout
Kill 100 Orks
Destroy a Lord of Skulls
Win a battle
Kill 100 Chaos units
Win a sandbox game
Win a multiplayer game
Kill a Freeblade
Destroy a Shadowsword