The heroes that we haven't all heard about

the story is kinda week because it's over the top while also trying to tie in with everything from the movies. You get to defeat the balrog and fight sauron.
The gameplay on the other hand was quite fun for me, because it used a turn based combat with some depth and there wasn't much grinding needed to go through most of the game. It also allowed to use the evil guyes after you completed the chapter. it was fun "assaulting" helm's deep and minas tirith.

I wish! ;)

Actually though I went through my entire library on steam and gog and my few physical games and it's surprising how many fail to meet this criteria, and most of my games are rpg, rts, or other strategy games that take place in established settings such as LOTR, DND, Warhammer, etc.

I could branch out and consider things outside of gaming of course. Two of the most obvious are Torchwood and the Sara Jane Adventures, spin-offs of Doctor Who.

Many shared-world settings in literature have stories that could be considered this; an individual squad's experiences during an interstellar war, or some of the Dragonlance saga stories in which the War of the Lance is viewed through the lens of different characters. It's been over a decade since I last picked one of those up but I feel like that's still right.

Good luck with your search.