Tienna
You all come from the planet Tienna.  (You are now on Allevia, its sister planet.)

You come from the Krusark Kingdom, which is predominantly human.  King Thresh III sits on the throne in the human kingdom.  It is relatively peaceful, but rumors of a coming civil war are in the air.  You are King Thresh's servants, knights, or warriors who go on missions for him.

You have never heard of orcs, though goblins are developing clan rules in the Kurshyk Kingdom.  Dwarves and elves

While out and about, you were approached by a mage named Azaron Ashe.  He led you to the Valley of Mist, where magics are concentrated, according to legend.  Once there, he led you to a portal and said it will take you to the planet Allevia.  You have heard legends of Allevia being rich in magic and treasures, but he said you should seek out the Artifacts of the Five Pillars and prevent them from falling into evil hands.  You know little about these artifacts, but he assured you that the knowledge would come in time.

You each agreed to this journey for your own reasons, partly because Ashe is counsellor to King Thresh and you felt an obligation to do as he says.  Now you may regret the decision to some extent.

Allevia

You started with 8 men.  You came through the portal into these tunnels but became turned around.  At one point you found what seemed to be a way to an exit, but giants were around and you had to retreat.  There were strange creatures (see the viper they just fought) which also drove you back, and you hear strange voices which seem to be giants who dwell within the caves and may still be blocking the exit.

One man died from one of the viper attacks.  Three others died from a strange disease that seems to attack those in the caves, but you don't know of its origin.  Then, during a battle with one of the giant viper creatures, a cave in fell and blocked Hatchman and Donovan.  Lukas has been helping with making sure they have sustenance and making sure they are safe from further attacks, but the rocks are too heavy for him to move.

You lost track of time in these caves, but your food supplies are low.  You would guess you were there between a week and 10 days.

You escaped the caves, crossed a bridge to escape the giants, and found yourself in a temple embedded in a mountain. You fell down the length of a mountain into water, only to find yourself face to face with the dragon, Ozymandius. You escaped, only to find yourself in the bizarre outside area where the ground changes by day based on the mist. Only the rocks keep you safe from them. A village of gnomes took you in, and now you search for the cure to the disease that afflicts those who have been in the caves and mountain temple too long. You have been on this planet for less than three weeks...

The Disease
The strange disease (The Black Curse) seemed to set in for some individuals within 1-2 days after arrival on Allevia.  It had the following symptoms:

The extremities become dark with pooled blood.
There are complaints of numbness.
The lips and throat swell up.
All this happens within a matter of hours of the first symptoms.

The last symptoms are insanity and pain.  One of your group attacked you in craziness and pain, and you had to kill him.  Another sat down and moaned, scratching at his own throat and stomach and finally stabbing himself to death in the gut.

...and your group was down to 6.