I think basically calculate the grapple score for the NPC's would be the main issue. Some skills have been combined, like Stealth now is used for move silently and hide in shadows and Perception is used for all of the sense skills.
There are a few new feats and a couple of the monster abilities have been tweaked a little. However, the monsters could be run as is, and the feat names are somewhat self explanatory. All of the information for specifics on them are available here, so you would be able to use them in 3.5.
Here's a free conversion guide that showed how to change from 3.5 to PFRPG. You could easily use it to change PFRPG back to 3.5 too.
Hope it helps. Personally, this is my favorite AP since the Rise of the Runelords story.
How tough would it be to run Kingmaker using 3.5 rules?
Trivial. Just pick it up and run it. There will be very few hangups.
...but Kingmaker would fit soooo nicely in my campaign...
This is the bigger issue. The plotline of Kingmaker doesn't "fit into" other campaigns easily. It is a campaign in-and-of itself. The APs in general don't piggyback well: you join at first level, and then level up with the adventure, and then you're done in the high teens. If want to not level up with the adventure (say, you wanted to run the entire thing at level 8 so you could fit it inside another campaign) that would require massive conversion work.
During the Kingmaker adventure path how often are monster stats referenced via the Pathfinder Bestiary? If I am running this AP in 3.5 will I not have stats for monsters because they are in the Bestiary (which I don't have)?
In the 3.5 APs monsters often just have a reference to the page in the MM. If Kingmaker does this with the Bestiary I'm concerned I will have to do a lot of swaps with equivalent MM creatures.
They do this in this AP as well. It's one of the ways they can save space, by not putting full statblocks for creatures that are part of the core assumption (i.e the Core Rulebook and Bestiary I).
However, most of the monsters can be found in the 3.5 MM I, or all of them can be found in the Pathfinder Resource Document . It will mean a little more work, as you'd probably want to have printouts or notes on hand for those monsters, but I'd want that anyways if I was running it in PF for ease of reference during combat.
Anything from PFRPG would add 1CR to it's 3.5 equivelent. Easy conversion there.
One potential problem is that, IIRC, Kingmaker uses the medium XP progression. I don't recall how that lines up with 3.5e progression, but it might create a situation where 3.5e characters are advancing much quicker than the adventure assumes.
Of course, if PFRPG encounters are tougher, that might be a good thing.
How tough would it be to run Kingmaker using 3.5 rules?
Players and I haven't made the switch to PFRPG yet, but Kingmaker would fit soooo nicely in my campaign that I'm itching to try it anyway. How much conversion would be necessary?
The Bestiary has critters that aren't in the 3.5e Monster Manual. I haven't looked whether any are used.
And whenever there are stat blocks, they are in Pathfinder, meaning you might see stuff like "Rogue Tricks: Combat Trick, Bleeding Wounds" in a rogue stat block or "Mercy (Shaken, Disease)" in a paladin's. Stuff the 3e classes have no analogy for.
In those cases, I suggest having the PRD open (or the Pathfinder book if you have it already).
But I also recommend taking this opportunity to make the switch. There is a significant increase in arsekickage involved in PF. Most classes have more options, there are a lot less dead levels, power levels have been brought closer (there are no more "loser" classes) and so on.
This is the kind of stuff I am concerned about. How big of an issue do you think this is? Does it get worse at the higher levels (I imagine it does)? Is the kingdom building stuff workable in vanilla 3.5? We're just not going to convert the PF so worse case I'll just run one of the other 3.5 APs instead.
I think it gets better at higher levels. That may depend on what sources you allow for 3.5. If you are just using the Core PHB, then Pathfinder characters will be a little tougher at higher levels. If you allow all sorts of splat books, your characters will easily be on par by about 5th level or so. It's also easy enough to give characters a boost by handing out a little extra treasure.
I think you'll find it fairly seamless to adjust back to 3.5 if you are super picky (OMG, that monster has 1 too many feats!). As the game evolves you'll be able to judge by their progress. Also remember that kingmaker is a little old-school with the exploration and wilderness encounters. If your second level group runs into a pair of trolls, they'd be wise to retreat whichever system you are using.
The Bestiary has critters that aren't in the 3.5e Monster Manual. I haven't looked whether any are used.
I know there were some critters from Tome of Horrors Revised updated with Pathfinder stats. Especially some fey, like mites and quicklings. But while it may be helpful to have a ToH, I don't think it would be terribly difficult to run from the Pathfinder stats. And I don't think those encounters were necessarily central; one might substitute for other fey.
Is the kingdom building stuff workable in vanilla 3.5?
I don't see anything there that isn't a problem to change. In fact, I could see it working in Cortex, L5R or WoD with just minimal changes.
The monetary limits in the city (maximum GP value and the like) work differently than in 3.5, but that should not be a problem to switch.
It also gives you experience bonuses for reaching certain limits and goals (kingdom size greater than X, establishing a capital, and so on) which are given in flat PF XP values, so you'll have to convert them to CR values to work with 3.5s system of XP by CR cross-referenced with level (and different amounts of XP needed to reach new levels).
But none of this is difficult to adjust.
The Bestiary has critters that aren't in the 3.5e Monster Manual. I haven't looked whether any are used.I know there were some critters from Tome of Horrors Revised updated with Pathfinder stats. Especially some fey, like mites and quicklings. But while it may be helpful to have a ToH, I don't think it would be terribly difficult to run from the Pathfinder stats. And I don't think those encounters were necessarily central; one might substitute for other fey.
Well, they're in there with full stat blocks, so that should be alright.
