Take Halbarad for instance, since we're diving on the ranger hype here, meld him into a player character or important main character, let it begin some time before the War of the Ring launches. Make it start in a short while before the 22nd of September T.A 3018, get to know the Rangers and their background a bit, get a connected feeling with some of them by preforming whatever task you fancy, then the 22nd hits.
Ringwraiths assault Sarn Ford, you are there and try to fend them off to no avail, they invade the Shire in their everlasting search for Baggins. Darn, that's a shame, I lost some of my kin to those scoundrels, emotion sets in, bury the fallen at wherever would make sense and then you get a call from Elrond. Halbarad is to assemble a group of thirty rangers strong. You, the player, are the messenger and are to unite the rangers chosen by Halbarad under the standard of the uncrowned king of Gondor.
Here's where the world starts to open up and you get more freedom to explore. Make it like the Witcher 3 where it's a multi-region open world, at least that would be my preference. Travel to the Lone-lands, Trollshaws, North Downs, South Downs, Bree-land, go to Forochel for all I care, just make it a visual, immersive experience that stays true to the way Tolkien described those lands. Once gathered, the Rangers will meet in Sarn Ford again or something. A task has been given, speeches are said and the Grey Company is born.
Trek through some of the previously mentioned area's and new places like Enedwaith, Dunland, The Gap of Rohan and stop at Dol Baran. Hey, guess who? It's ya' Chieftain and co. Your captain Halbarad hands the standard crafted by Arwen to your Chieftain Aragorn and the company joins forces. Oh, did I mention Elrond's sons are already in your company as well? That being Elrohir and Elladan, I should've mentioned that before, my apologies.
Not stopping here, lest Monolith fucks up even this part and injects your character with awesome ghostie powers in the Paths of the Dead. You venture forth from Dol Baran, having of course also handed the message from Elrond to Aragorn to venture through the Paths of the Dead. And so, being the good man he is, Aragorn heeds the advice of the Elf Lord and goes through the spooky passage. Hey, here comes the creepy part of the game, Dimholt is your first obstacle, room to innovate from now on, let some Orc tribe from the White Mountains bother you or something, lose a few men during some conflicts, beat the tribal chief and push on into the Dwimorberg, leaving behind angry orcsies who are too scared to chase you into the haunted mountain.
MAKE THIS PLACE EXPLORABLE, I want to see every nook and cranny of this passage, make it a few ingame days long, the trip that is, show vague signs of ghosts appearing around you and let Gimli blow wind against mist hands (everyone has to have loved that scene in the Return of the King). Eventually you meet the traitors to Isildur's line and let fear play a factor for some of the Rangers, driving maybe one or two in despair or whatever kind of edgy nonsense you can come up with. Make Aragorn say his lines, escape the 'berg, King of the Mountains swears his allegiance, we're all best friends, que Blackroot Vale, be creative and let the PC meet Duinhir while scouting ahead for danger or something, learn of the events that happened in Gondor, trot back Aragorn, inform him, continue through the wilds past the Stone of Erech, let Aragorn or Halbarad explain how diddly damn important that stone is, encounter a few threats on the way to Pelargir.
Here comes one of the big battles, or well, big scares. Stealth exploration, everyone loves it, Monolith can do that right at least. Take out some corsairs over watching the gates with a small group of rangers, open the gates for Aragorn and friends, let dead army scare corsairs, they dive in the Anduin or flee elsewhere, take ships, profit.
And the final battle, the end of your journey, the Battle of the Pellenor Fields. Make it a big vista, layed out with corpses of horses, wargs, orcs, men, corrupted men, mumakîl, trolls, you name it. And in the background, display the glory that is Minas Tirith, with Grond at it's destroyed gates and remnants or Orcs still streaming inside the city. Fighting ensues, the big battle you've all been waiting for, it's here. Shame your captain Halbarad doesn't survive and most of the Rangers die.
Now here's my preference. You die fighting a one on one fight with a Morgul lieutenant. None other than Gothmog himself portrayed as a Black Númenorian. Watch with your dying breath how Gothmog yanks his sword out of your chest and leaves you to die in the dirt. Life is slowly draining from your body, you don't have long. Que cutscene where you see the fallen around you, look up with your last power and watch Aragorn fight to avenge his fallen kinsmen, Aragorn slays Gothmog and you know you've been avenged. Your chieftain hurries to your near dead body, says some short senitmental sindarin nonsense with subtitles. Game ends with a sad ending for your character, but you can watch some scene where Aragorn fights at the Black Gate, damn near dies untill Frodo lobs the Ring in Amon Amarth (not the band, that would make the world we live in collapse) and saves the day. Eye explodes, tower tumbles, game ends. Que credits with a nice background score.