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