Knights & Knaves Alehouse

What is the difference between OD&D and AD&D?
I play AD&D 1ed.

Depends on how much of the various supplements of OD&D you use.

If you're using all the supplements (Greyhawk, Blackmoore, Eldritch Wizardry) and some articles from The Strategic Review and The Dragon, you pretty much have AD&D. There'll still be some differences (3- or 5-prong alignment, AC starting at 9 instead of 10, some of the HD for classes, etc.) but it'll largely be the same thing.

AD&D added some things that weren't in OD&D at all... the Half-Orc and Gnome, for example. Spell casting time and segments are another thing. Pretty peripheral stuff.

However, if you just take the original boxed set rules, and then add on to and interpret them as you wish (instead of how others subsequently did), you could end up with an extraordinarily different game. There are only three classes, you could interpret the language on spell casting pretty differently than what became the common understanding of "Vancian" magic, hit points could be worked very differently, combat could be worked very differently... You could use add ons from, say, Arduin or Judges Guild or a couple dozen other sources... It'd still be OD&D, but it'd be very different from AD&D.

I just recently got the "5.5" edition of Tunnels & Trolls. It's nothing at all like AD&D. But it's quite easy to tell how St. Andre made some interpretations and changes to the OD&D rules to get to Tunnels & Trolls. I'm not picking on T&T. (I think it's a fantastic game!) I'm just using it as an example of how OD&D is a fountainhead from which all sorts of different games can come.

If you don't have it, I strongly suggest you go download the original D&D rules. Just $5.99.
http://www.rpgnow.com/product_info.php? ... 28306&it=1

rogatny has the right of it.

If you're interested in some of the specific differences (especially focused on the three brown books without much from the supplements), check out my OD&D-oriented web site (see the link in my sig).

You might also try looking at both Mythmere's excellent Swords & Wizardry (OD&D) & OSRIC (AD&D) for a clearer comparison of the two. OD&D really is a "come as you are, go as you please" kind of game, whereas AD&D is a standardized system for tournament play that incorporates a lot of Gary Gygax's campaign material.

Thank you.