For some reason I had the impression I knew TATW even before I was exposed to it.
And this morning, it struck me. It's an upgraded, or a realistic version of Heroes 3.
If you think about it:
Castle is Gondor
Silvan Elves, Lothlorien and Fangorn are Rampart
High Elves have a penchant of Tower to them
Rhun is Stronghold
Harad is Fortress
Isengard is Inferno
Angmar/ Dol Guldur is Necropolis
Mordor is Dungeon
Or maybe it's the other way around. Heroes 3 is just a simplistic copycat for the Tolkien universe.