Then the other thing occurred to me - there are a lot of similarities between the editions, at least on a broad scale. To make things a little more interesting, I have also got the PDF of the OSRIC rules, which basically reproduces the basics of 1st Edition AD&D.
Here's a quick run-down of the classes in the Players Handbooks for each
|1st Edition/OSRIC ||3rd Edition/OGL ||Castles & Crusades|
|Fighter ||Fighter ||Fighter |
|Cleric ||Cleric ||Cleric |
|Thief ||Rogue ||Rogue |
|Magic User ||Wizard ||Wizard |
|Druid ||Druid ||Druid |
|Paladin ||Paladin ||Paladin |
|Ranger ||Ranger ||Ranger |
|2nd edition Bard ||Bard ||Bard |
|Monk ||Monk ||Monk |
|Assassin ||? ||Assassin |
|Illusionist ||Specialist Mage ||Illusionist |
|? ||Barbarian ||Barbarian |
|? ||? ||Knight |
|? ||Sorcerer ||?|
- The Monk was left out of OSRIC, but it's definitely there in the 1st Edition AD&D PHB.
- The Bard in 1st Edition AD&D is too much like a prestige class to be considered the equivalent to the 3rd Ed and C&C Bard, but the bard from the 2nd Edition AD&D PHB is close enough.
- The Illusionist is found in all 3 editions plus C&C, but in 3rd Edition they are lumped together with specialists of other schools of magic. This is also true of 2nd Edition AD&D.
- The Assassin is a basic class for both 1st Edition and C&C, but the assassin in 3rd edition is a prestige class. There have been 3PP versions of the assassin as a "basic" character class for 3rd edition, but I do not expect other people to have those to hand.
- The Barbarian is there in both 3rd Edition D&D and C&C, but not in 1st Edition AD&D or OSRIC, unless you include the Unearthed Arcana barbarian, which I consider horribly broken and unbalanced.
- The Knight in C&C has no real equivalent in the other PHBs - there is the knight in 3.5 Ed PHB2 (which has a similar role), but I don't expect many people to have that, and then there's the cavalier from Unearthed Arcana for 1st edition AD&D, which, like the UA Barbarian, I have not included as I consider it to be too broken and overpowered.
- The sorcerer is only found in 3rd Edition D&D and has no real equivalent in either 1st Edition or C&C.
If I had a wish-list, I would want a widely accepted Assassin class (basic, not prestige) for 3rd Ed D&D, and a better-balanced Barbarian for 1st Edition AD&D/OSRIC. The 3rd Edition sorcerer and C&C knight I would just leave alone. Then I would have a commonly agreed group of core classes across D&D and C&C. The sorcerer and knight I suppose you could have as optional classes.
Races: The basic races are common across all 3 sets of rules that I mentioned: humans, dwarves, elves, halflings, gnomes, half-orcs and half-elves. Subraces tend to be more a matter of what world/campaign setting you play in than what edition you use. Race/class combinations do vary between the different systems but I've never really considered those to be too important. Actually, for C&C it seems to be preferred classes rather than restricted classes while for 3rd Edition D&D each race has a favoured class, with no serious race/class restrictions, so that just leaves AD&D/OSRIC with the heavy restrictions.
Levels are the equivalent for each system. 1st Edition AD&D has stringent level limits on demihumans, varying on which class they take. When playing 1st Edition, I actually used the 2nd Edition optional rule that once a demihuman character has reached their "maximum" level they may still progress but needing double the normal XP. This makes humans still slightly more attractive, at least in the long-run.
Alignment is exactly the same across these versions - the combinations of Law or Chaos, Good or Evil and Neutrality. The only problem is that 3rd Edition is more relaxed about alignment requirements for classes, particularly druids and rangers.
Ability scores are the same names for all 6 (Strength, Dexterity, Constitution, Intelligence, Wisdom and Charisma) and all range from 3-18 with a few exceptions - 1st Edition AD&D uses 18/ % strength, while 3rd Edition and C&C do not. Also 3rd Edition D&D racial bonuses and level bonuses may increase ability scores over 18, while other editions do not allow for that.
I think what I am trying to get at here is that a lot of stuff could be interchangeable between C&C, 3rd Edition D&D and 1st Edition AD&D/OSRIC so long as you keep things very general and don't get too into transfering combat stats, class abilities or saving throws. Those sorts of details are probably best done separately for each edition. A DM/Castle Keeper wanting to transfer material from one edition to another will, I expect, need to make some compromises and some fudges, particularly for some of the more unusual classes. This is ok as far as I am concerned. Once you are willing to make those compromises, a whole lot of material becomes available for the players of any edition.