It seems that in real life HOMM4 hit store shelves one day before MM9.

But what is the relationship between the two in terms of gameworld time? Are they more or less simultaneous? Do the events of HOMM4 happen first or vice versa?

I think, they are more or less simultaneously.

But really there is no connection between those two except both have the stories happen on the world of Axeoth.

MM9 does not even mention the destruction of Enroth, I believe, which is shown in the introduction of HoMM4.

If anything HoMM4 might be a little earlier than MM9 as it starts with the destruction of Enroth and the refugees finding themselves in remote places of Axeoth, none of them seems to be Chedean where MM9 takes place.

Also, events from MM9 are not mentionend in HoMM4 and vice versa.

I think PiercedEye is right in which that Homm4 is definitely the direct continuation of Heroes Chronicles and MM8; I don't think MM9 happens until way later when the Enroth survivers have at least established and settled upon Axeoth. That said; I still doubt much thought went into continuity during the development of MM9. I'll always feel that destroying Enroth was NWC's way of rebooting the series and MM9 went out of its way to finally shed all reference to the increasingly elaborate storyline that originated from MM1 and Homm1 (The Enroth/Ironfist storyline) and ultimately linked the RPG's and HoMM together in MM7.

Such a shame really, one of the many reasons why MM9 was a bomb in my eyes. At least HoMM4 tried to give the fans closure.

Thanks for the follow-up, fellas! I had planned to play HOMM4 first, so I guess I'll just go forward with that plan.

I have pretty low expectations for MM9, so I'm hoping to be pleasantly surprised. :^)

You won't. Story in HOMM4 is actually pretty good. On the other hand, story in MM9 is a complete and utter bulshit. The only connection whatsoever with the previous games is one npc, and he appears to be mentally handicapped.

Haha! Oh well. I've got a goal to finish up all the NWC Might & Magic games. So, we'll see how it goes for me.