Quite slowly. I'll have to take some time out to write down some plans on paper regarding what needs to be done next.

Yeah the THV's seem counterintuitive to me too at this stage.

Let me show you another function, this time from item.cpp:

long item::GetBlockModifier() const
{
  if(!IsShield(0))
    return GetSize() * GetRoundness() << 1;
  else
    return GetSize() * GetRoundness() << 2;
}

I don't know how it works because I have not stared at it for long enough. It gets called inside this function in bodypart.cpp,

double arm::GetBlockValue() const { return GetToHitValue() * GetWielded()->GetBlockModifier() / 10000; }

when the game calculates the BlockValue of an arm, for blocking.
It would seem that the blocking value of a shield is modified by its roundness and size.

What about permanent polymorph into an orc, by drinking a potion or something? Then you can play the rest of the game as an orc character.

Is there any code for the Magic 8 ball, by the way?

Also, now I think about it, I think the devs used bitwise operation in place of floating-point operation as often as possible because it may be faster. I'm not a computer engineer but I recall that bitwise operations are a more fundamental structure inside most modern ALU's. Geek geek.

It's in item.cpp, and the function goes a little something like this:

int item::GetStrengthValue() const
{
  return long(GetStrengthModifier()) * GetMainMaterial()->GetStrengthValue() / 2000;
}

Regarding the bitchift operator, you are correct. If k = BlockSinceLastTurn and (1 << k) signifies a 'left-shift' operation, then this is the same as multiplying the first operand, i.e. 1, by 2^k. F. ex. 1*2^k: 1*2^2 = 4.
Really it's like this: 0001 << 2 = 0100 = 4, (in binary of course). All the bits are shifted two places to the left.

I agree with all your observations of the code you mentioned here:

if(RAND() % int(100 + WeaponToHitValue / BlockValue / (1 << BlocksSinceLastTurn) * (100 + Success)) < 100)
then (block)

Isn't the THV just the ToHitValue of the weapon/item?
With a little sourcediving I think this may just be the case. The THV flows through several functions before finding its use in the blocking function, but I think it originates inside bodypart.cpp. Specifically, the game checks to see if the character is wielding something, and then calculates a THV (of the item/arm) based on what is being wielded (or not).

Therefore, in bodypart.cpp we have this extremely interesting piece of code:

double arm::GetWieldedToHitValue() const
{
  int HitStrength = GetWieldedHitStrength();

  if(HitStrength <= 0)
    return 0;

  citem* Wielded = GetWielded();

  double Base = 2e-11
		* Min(HitStrength, 10)
		* GetHumanoidMaster()->GetCWeaponSkill(Wielded->GetWeaponCategory())->GetBonus()
		* GetCurrentSWeaponSkillBonus()
		* Master->GetMoveEase()
		* (10000. / (1000 + Wielded->GetWeight()) + Wielded->GetTHVBonus());
  double ThisToHit = GetAttribute(DEXTERITY) * sqrt(2.5 * Master->GetAttribute(PERCEPTION));
  const arm* PairArm = GetPairArm();

  if(PairArm && PairArm->IsUsable())
  {
    citem* PairWielded = PairArm->GetWielded();

    if(!PairWielded)
    {
      if(Wielded->IsTwoHanded() && !Wielded->IsShield(Master))
	return Base * (ThisToHit + PairArm->GetAttribute(DEXTERITY)
		       * sqrt(2.5 * Master->GetAttribute(PERCEPTION))) / 2;
    }
    else if(!Wielded->IsShield(Master) && !PairWielded->IsShield(Master))
      return Base * ThisToHit / (1.0 + (500.0 + PairWielded->GetWeight())
				 / (1000.0 + (Wielded->GetWeight() << 1)));
  }

  return Base * ThisToHit;
}

I think it calculates the THV and hence the WeaponTHV in the block. I think it bears resemblance to the parsing shown by Squash, no?
It's getting a bit late for me atm, but hopefully this provides more clues.

I'm looking at this presently:

I calculated the StrengthRequirement = 0.153.
Therefore, HitStrength is indeed 19, as Izzy has calculated.

in Bodypart.cpp there is this function:

int arm::GetBlockCapability() const

This function returns the value of the block capability of a humanoid's arm as follows:

Min(HitStrength, 10) * Wielded->GetStrengthValue() * GetHumanoidMaster()->GetCWeaponSkill(Wielded->GetWeaponCategory())->GetBonus() * (*GetCurrentSWeaponSkill())->GetBonus() / 10000000;

The first part is a Min function, which takes the minimum between two values f.ex. HitStrength and 10. So the result of Min(19, 10) = 10.

Next I calculate the strength value of the Short Sword to be (90 * 200)/2000 = 9

I do not know how to calculate class skill bonus or specific skill bonus so will assume they are as above, i.e. 1400 and 1450 respectively.

Then I have:

Block Capability = 10 * 9 * 1400 * 1450 / 10000000
                                  = 18.27

That is all I have for the moment, hope this helps

I can't remember where the worst item list is, but this fella was carrying a very unfortunate weapon:

My guess is that the magic mushrooms need to "smell" in order to undergo some kind of sexual reproduction. Their gametes are the magic clouds.

What you need is to edit the script file, char.dat, in this way:

...
magicmushroom
{
  ...
  ClassStates = GAS_IMMUNITY;
  ...
}
...

Good idea about the tree-wall tileset. I'll get working on it once I have time again. I started my new job and it definitely demands more attention than slacking around at varsity. Maybe I can make hedges, and then build a hedge-maze level. \o/
All I have to do is make the levels "IsOutside = true" and make the solid earth terrain resemble the trees. I'll also need to fix the earthquake bug if this happens, to prevent the infinite loop. Maybe open terrain needs a separate earthquake algorithm.

Hmm, I'll definitely make the characters you mentioned a bit tougher. I think there may be too many monsters on the bridge and the prison. If I lower the amount, I'll have to increase the difficulty level or the respawn rate. 1.5 is pretty big, but I'm sure it will be a worthwhile victory to pursue if I tighten some of the loose screws.

I must also remember to tone down the old Dragon Cuirass... maybe they should be made of stone materials.