Return of Mystara?

[Mystaros]

I'm planning on running a HackMaster adventure based loosely on the (delightfully poor) movie adaptation of H.P. Lovecraft's Dagon. I kind of would like to set it on an island in Ierendi, but would like just a few minor spoilers from the newer version to help start up the characters.

Sounds intriguing! You will definitely have to let us all know how it goes...

1) What timeframe (or equivilent) is the HackWurld book set in? 1000AC? 1014AC?

The HackWurld will be presented as of 1000 AC, the time from from the Gazetteers, before the Wrath of the Immortals.

2) Do the Immortals exist as in the Known World, or does the HackWurld use the standard Gawds of Twilight Last?

It will use both. Exactly how, however, will be a surprise... Feel free to use them a mix and match for now, as the book will have full details on how this work for the Immortals and Gawds in general, and regional details in specific.