Zeus said:
As for the Tower... well, I know I'm not going to run this kind of scenarios. First of all - some of my players know the stories. Besides, it requires creating an alternative setting, where Conan didn't do this or that. I'd prefer a scenario based on the consequences of Conan's deeds - returning to Xuthal, Olgerd Vladislaw's revenge, or something like that. I have already tried this with 'The Black Stranger / Treasure of Tranicos' and it was fun to see my players struggle in a familiar setting for an already plundered treasure (I assumed that Conan took it eventually - cruel, yes, but still fun for both sides

).
I understand your concern about adventures "altering" the Conan timeline, but I wouldn't assume that the Tower stories would have to alter them. I ran PCs through Zamboula, through the same temple that Conan went through, with many similar features, but it occurred before/after Conan's events there, so no big deal. Is there a description of the Tower stories that would suggest "altering" the Conan timeline by PC involvement? If not, then it well could be designed as (1) events in the Tower while the master is away, (2) events in a subsequent Tower by another mage who had spied on the master, learned how to make it (even acquiring another alien, etc.), (3) or a myriad other options. And even if the adventure isn't so designed, you could readily modify it in such a fashion, and get plenty of use out of it.