This is excellent news and will add great replay value for the game! 

Here are some features the community would be interesting in modding: 

1)  New Races/Nations:  And the related details(spells, technologies, items, abilities, units, buildings, etc.,)

2)  New Terrain Types:  examples= Lava, Snow, Caverns, Tar Pits, etc.,

3)  New World Map Structures: examples= Gates, Mazes, Altars, Graveyards, etc.,

4)  New Channeller Shapes/Designs: examples= Saurons immobile flaming eye, Medusa(Gorgon), etc.,

5)  New Battlefield Skills for Units/Champions/Channellers: examples= Turn_to_Stone, KnockBack, Possess, Spray_Web, etc.,

6)  New Abilities for only Champions&Channellers: examples= Tunneling, Alchemy, Stealth, Assassinate, Tracking, Hibernate, etc.,

7)  Adding new game elements: examples= Merchants Guild(Another Trading Method), Arena Death Match (Each_Player_sends_1_Champion_to_Fight_for_the_Prize(s)),  Traveling Weather randomly moving on the World Map, Natural Disasters(Plague), Mercenary Boards(Temp_Hire_Mercenaries), etc., etc., .

8)  New AI Personalities:  Custom AI Scripting allowing the creation of unique interests, personalities and behaviors for the AI opponent.

Hope this helps.   

What is the scope of this? Are you aiming to have the game be so moddable that one could recreate, for example, a Civilization clone with it?

If yes, that would be awesome. (Although I know I shouldn't expect so much from any game.)

Sounds great.

What was the engine for Empire: Total War made for, if not specifically for a strategy game?

Greater developer support for customising a game is always appreciated though. Fans will get around recalcitrant developers if they must but the more open the game is, the more likely you'll get the "Counter-Strike" of strategy gaming.

Hm, I wonder how this game will evolve... I guess, it depends a lot on how user friendly the modding tools are. Can someone, who has never modded before, have an easy start with it and change the game to a total new one? Perhaps even without looking at code at all? This would be a daring task... And a fitting achievement for stardock as I learned to know it.

It would end up in having creator programs for everything: Units, houses, cloth, plants, beasts... Even rules for the game mechanics...

Edit: I know design programs will be included, but it seems as if this is becoming larger then I have ever imagined... Righ now the ELEMENTAL project sounds to me like getting a good turn based strategy game with the possibility to make any turned based strategy game you desire...

If you could make a Carcassonne total conversion you could probably make one for any board game as well. Ah, the possibilities...

And even better: Master of Magic reloaded.

It was made for a loading screen game!

Nice list. I wonder how the AI will be able to manage correctly all this kind of stuff.

Very nice to see such a strong focus on it.  I'm already pretty sure I, hopefully with others when the time comes, will endeavor to make a Roguelike from it/out of it! 

A damn solid list of suggestions so far; they all work for me.

Mikey Likey! Ah this is just another evolvutionary step for gaming, I'll probably have more fun making stuff than actually playing the game...well as long as modding will be noob proof...I'll admit it I'm a noob when it comes to modding (except when downloading them)

Such as, or is this one of those things only a professional would understand?  (The only thing that comes to mind is draw distance -- you need to be able to draw a lot more in terms of distance for a strategy game)

Keep those suggestions coming! Great Work!

So we would be able to mod a Hex grid into Elemental?

Would this involve licensing the engine or will a scripting language be included in Elemental?

Sammual

All hail the frog! 

Someone should re-make Archon in the Elemental engine.