Welcome Saesh, Darin says it all pretty well. Sounds as if you have a large repetoire of skills and all of them will be very useful here.
Truant has just sent me his updated version of Ventara so that town is just about ready for NPC's. However Ventara is very much a Mediterranean town so to speak. If you are interested in Northerness there is huge scope. As youve probably gathered by now Mesogea is a totally made up place, straight off the top of my head from 1991 onwards, with bursts of writing for a few years, then a break, then writing again. It began with little Mediterranean interest as more of a Norse story, then diversified (much of it when I developed an interest in Rome and much more so when I started my degree in archaeology and classical studies - part time as I work full time anyway.)
Mesogea doesnt entirely exist in my head, thankfully, I wrote lots of it down so there is plenty of info to draw from and I will post more of it now I think about it. Much of it I have decided by doing this mod, deserves to come from and exist in the heads of other people which is why I try to keep it as a fairly blank canvas. All I ask is that whenever anyone thinks about doing or adding anything they bend it into the pre history fantasy vein to keep the mod feeling as if its a jigsaw that fits together. Other than that its open season for you guys. If you do anything Norse/Saxon/Jute etc then try to come from the direction that Tolkien pretty much took regarding Middle Earth. He looked at true historical people and considered that their society sprang from something similar that had for one reason or another been almost wiped out for tens of thousands of years before coming back into existence.
Its the way I went with the Holorians, thinking, if the Romans, Greeks and Etruscans had a shared ancestry what in some fantastic, fantasy way would it have been forty thousand years ago before an Ice Age destroyed it. Gives a lot of scope for making stuff up I think.
Now we can have magic and sorcery, beasts and a totally fictitious history.
So, what to do, what to do. Absolutely tonnes of stuff. If you want to do some 3d work then there is a whole route you can go down. We need northern architecture and so forth, clothes, weapons oh my
If you want to pick an area of the world and develop it with civilisation, settlements, NPC's etc etc then wow, you have a huge scope for this one.
Take a good look around, see what you like, where the mood takes you and let me know.