LBB Hit Dice/XP Progression

I've ruminated about this a lot on my blog.

Up through 9th level, Fighter HD are pretty obvious: 1 per level, but a couple levels get a temporary bonus point. Clerics are almost like Fighters: 1 HD per level through 8th, but they don't get a full hit die at 5th level, just a bonus point, and they're 1 HD behind thereafter.

M-U hit dice are basically half the Fighter HD, round up, with a +1 point on each "repeated" hit die value. This simple relationship breaks down at 8th level (so one of the changes I'm making to my LBB retroclone to avoid infringement is to "fix" this.)

For Fighters of 10th+ level, Clerics of 9th+ level, and M-Us of 11th+ level, the HD progression slows: one HD ever other level for fighters, every three levels for clerics, and every four levels for M-Us. Fighters alternate between a +1 and a +3 hp bonus, while the other two have sequential hp bonuses (Wizard 11th level = 8 HD +1, 12th level = 8 HD +2, 13th level = 8 HD +3, 14th level = 8 HD +4, 15th level = 9 HD +1.)

You can calculate HD from level for name-level characters:

• Fighters: find (level -10)/2. Add that many HD to 10 HD +1; add double the remainder as bonus hit points.
  
• Clerics: find level/3. Add that many HD to 4 HD +1; add the remainder as bonus hit points.
  
• Magic-User: find (level -11)/4. Add that many HD to 8 HD +1; add the remainder as bonus hit points.
  

For experience, it's a little muddier. Fighters have a straight doubling every level, but only two significant digits are kept, so 8th level requires 120,000 xp instead of 128,000 xp. The basic principle for all classes seems to be that once xp exceeds 100,000, the table stops doubling and switches to adding instead. For Fighters, this means each level beyond the 8th needs another 120,000. Clerics require 25% less experience, Magic-Users require 25% more, but this relationship breaks down after a few levels, because of an arbitrary decision to simplify the upper levels and set 9th level sorcerers and 8th level patriarchs to 100,000 xp; the magic-user has too many levels before 100,000 xp to maintain the +25% experience requirement, so the requirements for levels 6 through 8 are adjusted to fit in the available space. Clerics, on the other hand, get a little penalty at 6th level to make their xp requirements line up with the 100,000 xp goal at name level.

So, my speculation is that the xp for name level was decided first, then the fighter progression was decided, xp for fighter name level was increased to fit the progression, and finally the pre-name level M-U and Cleric requirements were adjusted to fit the established patterns.

The 9th level fighting man (lord) is the equal of the wizard (level 11). Why does the wizard require Some 400,000 XP more than the fighter, don't let a love of Mathmatical formula get in the way of a good game.

The wizard is 11th instead of 9th because of how the spell system was translated from Chainmail to d&d, and doesn't mean that a 11th level fighter is the equivalent of an 11th level wizard.

All classes should hit name level at roughly the same time. This was gygax's logic as name level meant retirement or domain management. In your system, the wizard will never get a tower, because the Lord will have long since moved onto to other things or even leveled an entirely new fighting man to name level before the player of the wizard excavated his first dungeon laboratory!