For shadows : faked ones with a projected decal or textuer projection is the key : used a lot in commercial engine (Far Cry etc ..)
LOD is the another big key of big titles : play Guild Wars to see how it is used obliously

Now a question that will make you want to kill me
ok i'm going to troll a little ...
here it is ....

After playing Far Cry and finding it for 10 Euros in any shop ,
why should i play your game that is and will remain far far away ,
3DGS is not Sand box Engine at all ?

Any originality ? cool new features ? (crysis will have some little originality on alines and powers)

OR perhaps you are just making the game for fun , and just to offer a game that can bring fun in that case forget my trolling