In the circular shaped room in the middle of this rock formation:

__#__
_###_
##=##
_###_
__#__

Where:
_ is empty terrain
# is rock
= is stairs down

It's possible to generate extremely large continents. So yes, it's not surprising that you'd have difficulty finding the dragon tower, or that it be a long way off. The worldmap generation system is awful, and so probably needs to be looked at with some due consideration.

First off, to create a new location you will need some means of compiling the source files.
You can use IVAN CVS or LIVAN as a starting point, or you can also use CLIVAN, but personally I think it too buggy.
The header files like ivandef.h and wterras.h etc are part of the source.

To avoid compiling, there is a precooked map location in LIVAN.
What you can do, is use a normal distribution of LIVAN, and simply use the dragon tower (which is an unfinished location) on that map and use the script files to develop a whole new dungeon to your heart's content. Wizard mode to find this location.
In this way, you can help contribute to IVAN development by creating an exciting new dungeon for people to play. The dungeon script files are fun and confusing. But mostly fun. IVAN will crash a couple of times before you get it right. See if you can work out what ``BoundedRandom'' does. If you understand how it works, then you know the right shit for making beautiful dungeons with high replayability. The original devs were so clever. Hardest thing is to balance the levels, but if you use a spreadsheet and some rough calculations you will be sweet.

Whoa Azba, funny stuff man I didn't know it was possible to do that by changing the script files alone.

Cool man, the stun gas was surprisingly simple. But I didn't know such a combination was possible. Good innovating guys
In CLIVAN I did the following:

define.dat:

#define STUN_GAS (GAS_ID + 12)

material.dat

gas
{
...
  Config STUN_GAS;
  {
    Color = rgb16(77, 188, 252);
    NameStem = "sleeping gas";
    Alpha = 200;
    AttachedGod = SILVA;
    BreatheMessage = "It smells like drowsy in here."; 
    Effect = EFFECT_KOBOLD_FLESH;
    StepInWisdomLimit = 8;
  }
}

item.dat

gasgrenade 
{
  ...
  SecondaryMaterialConfig = { 5, MUSTARD_GAS, SKUNK_SMELL, FART, MAGIC_VAPOUR, STUN_GAS; }
  MaterialConfigChances = { 5, 50, 10, 1, 10, 50; }
  ...
}

I tested it out in New Attnam in combination with mustard gas and you can clear out Richel Decos pretty smartly.

There is also a chance you can catch vampirism from being bitten by a vampire.
When unarmed, the bite attack alternates between hitting and biting in this ratio:

truth humanoid::Hit(...etcetera

	if(StateIsActivated(VAMPIRISM) && !(RAND() % 2))
	{
		Chosen = USE_HEAD;
	}

I think it is 50% of the time an unarmed attack results in a bite when being a humanoid afflicted by vampirism.

Sorry lum4r, won't do it again

Yeah careful with the game balance.
You can create vampires by giving such a character a special bite effect. Just use the code from SPOILER ALERT. Click here to see text. to reproduce the life-drain effect as a bite effect. (Check CLIVAN code to see how this is done).

Trickier still is to introduce a PC state (like Hasted, Lycanthropic etc) called Vampirism and allow the player to drain life using his bite attack, and reprioritise this attack as the default unarmed attack. I balanced this out in CLIVAN by making it so certain PC's stats (wis, int and cha) would deteriorate faster (probably needs to go a bit faster).
Then think of a way to allow vampirism to propagate though the game (obvious one is chance of receiving vampirism if getting bitten by a vampire).

Ha great stuff Cap, works like a charm now.

I think there were calls from the community to allow the PC to harvest flesh from corpses using pickaxes (or hammers o.0)

I did not know about this functionality in 0.43. You must be a long time invisible stalker Chiko? Welcome