OD&D (really FMC) Like it's 1974

I have been running Caverns of Thracia with Fantastic Medieval Campaigns for quite a few sessions¹, and just about every session I have to stop and discuss with the players about how to proceed with a ruling. In the spirit of FMC, I have been doing my best to avoid backporting modern D&D-isms into the game. In fact, where reasonable, I do my best to make my interpretations different from later rpgs. So, without further ado, here are a bunch of my rulings for FMC:

• All HD are rolled every level—if lower than current hp, increase hp by 1 instead.
• Prime Requisites:
1. A magic-user’s prime requisite score is equal to their INT, plus 1 for every 2 points of WIS above 9. (So a magic-user with 12 INT and 11 WIS has a prime requisite score of 12+1=13. This does not require that the magic-user lower their WIS, unlike in B/X.)
2. A fighter’s prime requisite score is equal to their STR, plus 1 for every 2 points of INT above 9, plus 1 for every 3 points of WIS above 9. (So a fighter with 13 STR, 13 INT, and 12 WIS has a prime requisite score of 13+2+1=16.)
• A magic-user’s spellbook for a given spell level contains all spells of that level. (So a level one magic-user knows all level one spells.)
• Magic-users do not need to select which spells to memorize each morning, though they cannot cast the same spell twice in a day.
• Defeated monsters give 100xp per HD.
• PCs cannot level more than once from a single session, and any excess xp is wasted.
• Firearms!
• Phased initiative as described in Chainmail

There are also some situations in which I have had to make up my own ruling because OD&D/FMC² just doesn’t give any explanation:

• Monsters who level drain still deal normal damage, and do not insta-kill creatures with 1HD.
• This hasn’t come up yet, but I think I would have level drain limit spellcasting and to-hit bonuses. Unsure about hp, it could be fun to just re-roll it for the level you dropped to. I also am partial to making level drain something that can be cured with remove curse or similar magic.
• Characters who win initiative in a combat round may retreat from melee at half of their speed. Otherwise, characters can retreat from melee at full speed at the end of the round if they did not attack. (If a character has an ally in the same melee who can cover their retreat, they can move normally.)
• When oil flasks are thrown at a group of enemies, they save vs. dragon breath or take 1d6 dmg. When thrown at a single enemy, it is a normal ranged attack, but also deals 1d6 damage on the subsequent turn unless the enemy has some way to douse the fire.

These are house rules

• No clerics³ or thieves, and magic-users can cast cleric spells.
• Double bonuses on magic swords (i.e. a +1 sword is now a +2 sword)⁴
• Also note: FMC is pretty clear that the bonuses are not added to damage unless the sword has a slaying power or is otherwise attacking the enemies of its special purpose.
• Combat is done using the “weapon vs. armour” table from the appendix⁵.
• To-hit bonuses are calculated using the “to-hit bonus by HD” table in the appendix.

  Hopefully these give you something to chew on for a bit. It has certainly been a fun exercise for myself to try and make most of these rulings as if I did not have access to other D&D-likes.

  Notes

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  1. I don’t know how many because I haven’t been writing session reports. One of my players has been posting recaps in our Discord thread and I am eternally grateful. ↩

  2. I say OD&D, but I haven’t actually ever read the original 3 booklets. FMC is close enough, sorry to OD&D purists or whatever. ↩

  3. This post and this post elucidate why. ↩

  4. This is because of a blog post I can no longer find. In it the author was describing using Chainmails 1-on-1 weapon vs. armour table, and how a +1 on a 2d6 roll was *way* more impactful and made the swords really feel special. Doubling the bonus is close enough to being equivalent for me. ↩

  5. For which I have been using this google sheet I made to automate it. ↩