Here are answers to my 20 rules questions for the Vaults of Pahvelorn OD&D campaign.
Ability scores generation method?
3d6 in order. Greyhawk supplement ability modifiers are not in effect (ability scores will be handled as per the 3 LBBs). Human only to begin with. Other options may become available later in the campaign.
How are death and dying handled?
At 0 HP, make save versus death. Success = unconsciousness, failure = death. In addition, there are no fixed HP totals. Hit dice are rerolled at beginning of every adventure.
What about raising the dead?
Yes, but only dark priesthoods have access to such magic. The cost, both monetarily and otherwise, will be high.
How are replacement PCs handled?
Promote a retainer or make a new first level PC with 0 XP.
By situation, but probably group initiative as per Moldvay (d6 per side, highest wins, reroll ties).
Are there critical hits and fumbles? How do they work?
Not at this time.
Do I get any benefits for wearing a helmet?
No AC benefit, but helmets may help in other situations. Also, you can drink out of them.
Can I hurt my friends if I fire into melee or do something similarly silly?
Yes. By ruling. I will warn if there is a danger though.
Will we need to run from some encounters, or will we be able to kill everything?
Encounters will not be balanced. But remember that anything that is a threat to your characters can also potentially be used by your characters creatively.
Level-draining monsters: yes or no?
You will need to discover this through play. NPCs may have useful information, or you could do it the hard way: charge everything and see what happens.
Are there going to be cases where a failed save results in PC death?
At 0 HP, definitely. Potentially in other situations as well. Beware of poisons. You might want to research potential threats and antitoxins.
How strictly are encumbrance & resources tracked?
Using the LotFP system. Retainers are useful for carrying things, too.
What’s required when my PC gains a level? Training? Do I get new spells automatically? Can it happen in the middle of an adventure, or do I have to wait for down time?
XP will be awarded after adventures as treasure is spent, and levelling up can happen at the same time. Spells must be discovered during play or researched; no free spells on level up. Magic-users may acquire fewer spell slots upon level up, but saving throws are allowed to retain spells when cast.
What do I get experience for?
Treasure. Killing monsters awards no XP. But you may be able to sell some monsters, either living or dead, in which case they are treated as treasure.
How are traps located? Description, dice rolling, or some combination?
Anyone may locate traps by description and player skill. Thieves may “remove small trap devices (such as poisoned needles)” (Supplement I: Greyhawk, page 4).
Are retainers encouraged and how does morale work?
Yes, retainers are encouraged and common costs will be provided in another post. For sanity, it is suggested that the entire party (PCs + retainers) not exceed 12. War dogs are also available, but are one hit die creatures.
How do I identify magic items?
Paying a sage is the surest way. Detect magic can tell you that something is magic if it is not obvious, and read magic can sometimes be used if there are runes or other arcane inscriptions.
Can I buy magic items? Oh, come on: how about just potions?
Yes, some consumable magic items can be purchased, but it depends on the location. You may even be able to find the occasional permanent magic item for sale, but don’t count on it.
Can I create magic items? When and how?
Scrolls may be created at first level following Holmes rules (100 GP and one week of work per spell level; e.g., a scroll with a single third level spell will cost 300 GP and 3 weeks of time). Other items as per the rules in Men & Magic.
What about splitting the party?
Occasional scouting missions are fine. Keep in mind that the time of other players is valuable.