Is it actually possible to convince Gark to open the gate? I've never been able to. In my current campaign I kept going "Me is Chief Guthma!" but obviously that was never going to work.

No.
Get the key from the orc shaman up north and go open the key. I have never heard of anyone managing to get Gark to open the door. Actually, I dont think he can open it from his side.

I've never managed it either. I suppose if you had a player with a really high charisma it might be possible

IIRC not possible.

Hm. That's too bad. It's not like Trugnuk's that hard to fight or anything, but it might be interesting just for variation. Oh well.

You must remember that IWD2 is very Linear and there usually aren't multiple choices in certain situations. So behead the Ogre and forget talking your way out of it, it's not an option.

Hmm, i got him open the gate once, i thought you needed a password from someone who is further south, i think it was a goblin, but i'm not sure if i'm right about this.

Isn't that in the warrens?

Definitely.

Atari Man summed up the problem: this game is VERY linear. If you get bored try other races, other classes, other alignements, other stats, etc. There are minor differences... nothing to write home about however :(

Perhaps different solo combinations could bring about some more diversity. At any rate, everything would still be about the proportion between melee, archery, sneaking, divine and arcane magic. No subtleties other than a thousand ways of killing stuff. Sometimes you can avoid some minor combat by choosing the right option and having the right skill value, but that's about it. The killing solution probably still gives more XP.

yeah, I noticed that killing gives more experience in most cases...and you get some items to boot as well.
Usually if you talk your way out of a situation and for instance determine some "nasty" to leave, they don't leave their equipment behind.
I guess only if you played the game multiple times - for instance in Heart of Fury mode - and killing someone doesn't give any experience because of your party's high level...only then it's worth taking the diplomatic path.

Go tO the goblin in th south , kill some spider for hime , bring the spiders , he will tell you the password (kill all the spiders and bring them to him ) go to the "doorman" tell him the password and he will open you !!!
P.S. IWD2 is the most stopid AD&D RPG I HAVE EVER PLAYED !!!!

People who are confused as to what the original poster asked about:

Horde Fortress 1st map, where you meet Ennelia, there is a side entrance into the fortress via its underground warrens. The door is locked and Gark the Ogre wont open it for you. The key is found on the body of Orc Shaman Trugnuk, north part of the map.

Ancient Galatan and now this guy are talking of the password required AFTER you manage to get into the warrens. Please dont mix things up.

IWD:HoW was so much better :(

Face it everyone! If IWD2 was very non-linear it would be sweet. It's fun, it's addictive, it's action, but if it's linear then I'm through! That is the one and only bad thing about this game. Every path is set, and it's usually a bloody path. The gate incident is just another example of this.