:The player starts being able only to play one of the "good" races (Men, Elves, Dwarves, Hobbits) and they start as an adventurer, a treasure hunter.
This gives an immediate goal to the new player: find treasures!
Ideally each race will start in its own subzone with a few starting dungeons/places around. Then they will be directed to a few old places that could old treasures (recently discovered ruins, lost island in the sea, .. and even .. yes .. your preferred dungeon, the maze!). This should last until about level 20/25 (out of 50).
Then around those levels the game will arrange for you to stumble upon an artifact known as the Staff of Absorption. This staff is unusable by the player at first, and he will be instructed to bring it to keepers of knowledge in Minas Tirith.
On the way he will be ambushed by orcs. Should he survive the keepers will reveal the staff is unknown to them but they can analyse its properties. It can be used to absorb the power of things, or places. The player also mentions the ambush and through various clues the keepers seem to think the attack came from the far east, as orcs are not common anymore in the west. King Eldarion (son of Aragorn, remember this is set 122 years into the fourth age, Aragorn passed away a few years ago) sends you to investigate (and leave the staff in the guard of Gondor).
The player then ventures into a new wilderness map, that of the east, known as the Empty Lands (which are far from empty). There he will face parties of hunting orcs, trolls, undeads, ... and obviously concludes there is some evil at work there.
Through various ways he will learn the final truth:
Of the five Istari sent by the Valar to fight against Sauron we only knew the fate of 3 of them (Gandalf, Radagast and Saruman). It seems the two remaining ones (Alatar and Pallando) that have gone into the east have fallen too.
They have created a force to assault the west. But their goal is not actually to destroy it, or rather not directly. They seek the Staff of Absorption to use it in a very special place: Mount Doom. The place where Sauron forged the One Ring, and where it was destroyed, 122 years ago. Some of Sauron's evil power still lingers there and they want it. For with it they will gain a link to Sauron's master, Morgoth still banished in the Void.
Once this link is established they plan on summoning him back into the world.
Obviously the player needs to stop that. For that the Istari must die, or the Staff destroyed. But since nobody knows how it was made it is not possible to destroy it.
Once the player arrives on the last level, confronts and destroy the Istari (yeah dual boss battle!), he will notice a portal to the void was opened. It seems Gondor lost the staff while sending it to a secure location (fools!) and the Istari have got hold of it. So now the player must either find the staff again and use it to close the portal, or enter the portal himself, with slight hope of return and end Morgoth's spirit forever.
Voila!
This is obviously a rough scheme but it does not sound to bad to me (yet
Opinions welcome!
Merry christmas to you all!
) assumption they failed, quite fun that you use a staff (wizardly symbol), in fact there is a lot to like here!