Here is the full list of all 29 Rune Classic achievements.
Get all the weapons in the game.
Complete the game (any difficulty).
Complete the game on Medium difficulty.
Complete the game on Hard difficulty.
Defeat Sark Conrack.
Become Sark Ragnar.
Defeat the Dark Dwarf.
Drink 25 Steins of Mead
Get "First Blood" 10 times
Behead 100 opponents in multiplayer.
Defeat an enemy by setting them on fire.
Kill 100 opponents in multiplayer.
Beat an opponent to death with a severed limb.
Behead 25 opponents in multiplayer
Kill 50 opponents in multiplayer.
Behead 10 opponents in multiplayer.
Get a 10 player kill spree in multiplayer.
Kill 10 opponents in multiplayer.
Get beheaded in multiplayer.
Defeat the Trial Pit Beast.
Make your way through Hel's Chamber
Obtain all the Runes of Health
Eat 25 Lizards.
Kill 100 enemies while Berzerk.
Kill 250 enemies.
Kill 25 enemies while Berzerk.
Avoid the Dealy Dangler Fish.
Kill 100 enemies.
Kill 25 Enemies.