So, for those of you who have experience, what separates BECMI from AD&D, both in rules and flavor?
A lot less textually dense than AD&D 1E.
What is good about it, what is not good (Thief Skills, I know about), and how should a campaign for this be run? Would it be best starting with the B and E box sets?
If you want the BECMI experience, I'd suggest getting (pirated scans) of all five boxed sets. And plan from the start to make it through all five in a certain timeframe.
If you followed the XP as written, it's gonna be a helluva a long journey to the Companion (aqua green) Set! Me and my brothers played from 1983 (when I was 9) till the end of high school...at which point we just reached Companion Level!
I'd suggest that you set a time frame (e.g. 6 months or 1 year) for a sort of "cut-scene" approach, where you do pass through the key "events" in the BECMI progression: e.g. Basic level 1-3, Expert level 4 and 9 (Name Level), the first and last level of Companion, the first and last level of Master, and then one or more Immortal adventures. This could all be dramatically achieved in a relatively short campaign arc.
For Basic levels 1-3, I'd suggest you play through some or all of B1-9: In Search of Adventure and B10: Night's Dark Terror.
And then just do two Expert adventures, two Companion adventure, two Master adventures, and then end an Immortal adventure or two.
Or should I just grab a copy of Rules Cyclopedia off of eBay and make something from that?
Dude, if ya wanna play BECMI, then "cannot" use RC...that's a different edition. (Though yeah, it's 98% the same.)
Also, what do y'all think of the Known World/Mystara as a setting?
It's great. It's zany. It's a crazy patchwork quilt. Mystara ain't gonna be the "grimdark" world. It's like Saturday Morning Cartoon Action Hour.
There's something to be said for real-world cultures serving as graspable handles. "Okay, these people you meet along the road are basically Eastern Europeans. You're basically a Viking. Your buddy is basically an Arab. And you're travelling through a country which is basically the Medieval Byzantine-Greek (Eastern Roman) Empire, though with Classical Roman/Latin themes blended in. (Though some of these portayals were done hamhandedly, according to present standards, that doesn't invalidate the basic gist.)
I'd also play up there being Lupin and Rakasta (of various real-world based breeds) in pretty much every town. And Tortles too. They're like the dog-people and other animal-people you see in the city-scenes of Dragonball anime...people don't even bat an eye. They're just people.
Red Curse = mutant super-powers. I could do without the "drug addiction" aspect which was added on by the AD&D editors.
Immortal Rules = Superheros. If you count the Immortal-Level play (and why wouldn't ye?), Mystara is really the "superhero" setting of the D&D Multiverse.