Here is the full list of all 25 Vosaria: Lair of the Forgotten achievements worth 1,000 gamerscore.
Pickup 100 Health.
Vanquish 25 enemies.
Pickup 100 Armor.
Beat the first stage of the game.
Fire your first weapon 100 times.
Vanquish 100 enemies.
Vanquish 300 enemies.
Pickup 300 Health.
Pickup 300 Armor.
Find 5 Secret Areas.
Find ALL Secret Areas.
Pickup 3 Health Upgrades.
Pickup 3 Armor Upgrades.
Pickup 3 Ammo Upgrades.
Pickup ALL Health Upgrades.
Pickup ALL Armor Upgrades.
Pickup ALL Ammo Upgrades.
Obtain the first 3 Weapons and their Add-ons.
Obtain ALL Weapons and their Add-ons.
Beat the last stage.
Beat the third stage in Heroic Mode.
Find and read ALL the Log Files.
Destroy 500 enemies in Heroic Mode.
Beat the final stage in Heroic Mode.
Get all the other achievements.