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