@juergen_hubert I find the Iron Kingdoms interesting lore-wise: they canonically are NOT connected to the Multiverse, which implies a lot of things as far as DnD is concerned.
I have the 5E version and I'm disappointed with how the background is treated in IK: Requiem (no map, strong emphasis on history...)
There are interesting gameplay ideas though : it is implied that PCs should form a specific kind of group that will give them mechanical advantages, be it a scientist group or a mercenary company.
But I hadn't bought anything more than the Witchfire trilogy in the 00s and 3E... and regretted it. So I invested in the 5E version... and I don't think I'll play that campaign (that takes place roughly 10 years before Requiem.)