Here is the full list of all 28 Hnefatafl achievements.
Finish an online game of Alea Evangelii.
Capture the king while he is on the throne in an online game.
As the black player capture the king and another piece at the same time.
Defeat all black pieces in an online game.
Escape with the king in an online game.
Block all four corners while playing as black.
Block three corners while playing as black.
Block two corners while playing as black.
Win without losing a single piece in an online game.
Capture the king in an online game.
Win your first online match.
Capture the king next to a corner piece in an online game.
As black blockade one corner.
Capture any piece next to a corner in an online game.
Capture three pieces at once in an online game.
Capture two pieces at once in an online game.
As the black player build a cordon.
Win a game against the computer as the black player.
Win a game against the computer as the white player.
Win with only the king left as white or with only two pieces left as black in an online game.
Form a shieldwall and capture multiple enemies at once.
Capture an enemy piece by jumping over it with your knight.
Foteviken Tablut: Capture a black piece that is still in a basecamp.
Create your own variant.
Win as white player by escaping through an exit fort in an online game.
Join your first tournament.
Finish an online match using the quick mode.
Win a Berserk Hnefatafl online match.