I know, you’re wondering “How can cr0m, that paragon of Old School virtue and banner-waving Red Box champion speak SUCH HERESY! BURN THE WITCH!”
What can I say? A project like this is very near and dear to my heart. 3e D&D gave me hours and hours of fun, and the d20/OGL movement completely revitalized roleplaying games (not to mention allowing all my favorite retro-clones to exist). And then I ran across a thread on rpg.net about the same subject, that almost immediately veered off topic, but still got me interested to see if it could be done. So put down your pitchforks. Lower the torches. Let’s give this a shot.
It’s really easy to get bogged down in all the fiddly bits of the d20 system, so I’m going to work on something very limited in scope: porting Basic D&D to d20. I want to make something that could be used with monsters and treasures from the d20 SRD without any modifications (other than some omissions). Then, if I want to, I’ll add more levels, spells, tweaks, alignment systems, and all the other things that make it fun to hack any version of D&D.
Let’s start with the building block of the Basic D&D classes: the Fighter. And keep it simple by restricting our port to Basic D&D. In other words, levels 1-3.
So here’s the fighter for levels 1-3:
Seriously, the Fighter doesn’t increase his fighting ability until level 4 in Basic D&D!
On to saving throws. In Basic, the saves (and their d20 equivalents) are:
Death Ray or Poison (Fort) 12
Magic Wands (Varies) 13
Paralysis or Turn to Stone (Fort) 14
Dragon Breath (Ref) 15
Rods, Staves or Spells (Varies) 16
So basically Fighters are decent at Fort saves (~13), worse at Ref saves (15) and about the same at Magic saves (~14.5). If we decide that Magic == Will, no surprises here.
BAB HD Fort Ref Will
+1 1d8 +2 +0 +0
+1 2d8 +2 +0 +0
+1 3d8 +2 +0 +0
So for a difficult save (DC 15), our fighter is going to fail a Ref/Will save about 25% of the time–which matches up pretty well with Basic’s chart. Ditto for Fort saves, where he needs a 13 or better. (It’s almost like 3rd Edition’s designers were working from an older edition…)
Do you need Feats to model Basic D&D? Not really, but might as well use the various Weapon/Armor Proficiency Feats.
Fighter gets Simple and Martial Weapons and all Armor/Shield Proficiencies. Since Basic D&D doesn’t have any skills, we just use Attribute checks. BOOYAH, we’re done.
I don’t know what I’d do next. I’m tempted to do the Dwarf, since he’s pretty similar to a Fighter but with some interesting special abilities, but it might be a better idea to port over a goblin and make sure that our Fighter operates pretty similarly to the Basic D&D version against a typical 1st level foe.