World Tour through Modules
by Not a DecepticonDecided to look at Mystara modules and see what kind of world tours could be made possible with them and what locations could they take the party in what order. This writeup was very helpful
Starting point
B series is almost enteirly set in Karameikos. And a lot of them are the type that can be easily placed anywhere. I think B6: The Veiled Society is best suited for a starting point of World tour because it sends the party to an iconic location, the city of Specularum. In similiar vein, DDA3: the Eye of Traldar sends you to Black Eagle Barony. However, B2: Keep On the Borderlands may be the strongest alternative due to how iconic and beloved the Castellan Keep and Caves of Chaos are not just to Mystara or Karameikos but the game itself. If you have to start, cannot go wrong with a classic, right?
B4 the Lost City and B7: Rahasia are only of B series not set in Karameikos (unless you want to turn Ghost of the Lion Castle into full party module, which sounds like a lot of work). They have added benefit of being relatively close so you can play one after another. In fact, you could tie them in with M1: blizzard Pass or DDA1: Arena of Thyatis and DDA2: Legions of Thyatis. And both the M1->B7->B4->DDA1->DDA2 or DDA1-DDA2->B4->B6->M1 sequences make sense. It's also possible to pick a few of those modules and use B10: Night's Dark Terror to get the party to higher levels.
Mid-tier.
There is little competition here since X1: Isle of Dread is a great follow-up to pretty much anything and you could easily move from it to X6: Quagmire!, eventually with X8: Drums on the Fire Mountain. From X6 you could either go West to X9: The Savage Coast or North to X4: Master of the Desert Nomads and X5: The Temple of Death and from there to X9. then X10: Red Arrow, Black Shield could be used to bring you back to the Known World and then as a framing device to visit more of it, with the possibility of doing X7: War Rafts of Kron and/or X13: Crown of the Ancient Glory along the way.
I do see one alternate route. Go North to X2: Castle Amber in Glantri, followed by X11: Saga of the Shadowlord in Wendar, XL-1: Quest of the Heartstone in Ghyr and then X13. But I think the first option gives you simply more places to visit.
After that dropping the party to Norworld in CM1: Test of the Warlords is a nice possibility and a form of "settling down" with an option t still visit places like Alphatia.
Possible sequences:
Journey to the North: B6 or DDA3 -> M1 -> X2 -> X11 -> XL-1 -> X13
Right, Left, Up: (B6 or DDA3 ->) M1 -> B7 -> B4 -> DDA1-2 or B10 -> X1 -> X8 -> X6 -> X4 & X5 -> X9 -> X10 (possibly with X13 and X7) -> CM1
That is if you want to build such a campaign entirely from the modules, of course.