The soundtrack from Doom II
https://www.youtube.com/watch?v=Celrs8uSQk8

Oh my god! I could do this all day long!
Lets start with 3 or 4

Sword coast legend - Maintheme:
https://www.youtube.com/watch?v=nYVjtQaXl0A

Pathfinder Kingmaker: Maintheme
https://www.youtube.com/watch?v=nxKNtNU7a-I

Myst 3 - Maintheme
https://www.youtube.com/watch?v=Q5Wo5-B0rQ8

Jade empire - Maintheme
https://www.youtube.com/watch?v=63HEV4xcmvQ

Skyrim: From past to present:
https://www.youtube.com/watch?v=9Vqa2BczUps

Final fantasy 10 - Endingtheme
https://www.youtube.com/watch?v=3bv1oNp_wJw

Monsterhunter world: Maintheme
https://www.youtube.com/watch?v=q6vgNFxUu1g

Well, let's start with a few:
Ys IV: Crimson wings
https://www.youtube.com/watch?v=MroVDCngnJU
This is the J.D.K. special version, which, from what I understood, is the soundtrack of a PC98 version of the game that never got released, but served as a basis for other version.
Speaking of other versions, here is the PC-Engine CD version of that theme:
https://www.youtube.com/watch?v=uGvSf8s1OWU
Now this is quite impressive, it's like two versions of a same theme that tell different stories.

RoboCop (GameBoy): Stage 1
https://www.youtube.com/watch?v=r92Ljyp_VWE
It blew me away to learn that one could do such impressive things with a GameBoy. The rest of the soundtrack is quite fantastic too.

And finally, one that you probably all know.
Soul Edge/Soul Blade: Bravely Folk Song
https://www.youtube.com/watch?v=7pa-KcpZHrI
Well, what to say about this one, except that it could have been powerful enough to be a national anthem? Not to mention a national anthem in a minor key could have been quite original, at least I think!
And here is an accordion cover that in my view, makes it sound mor sad, at least at the beginning. That sadness fits quite well in my opinion.
https://www.youtube.com/watch?v=Pi0DiXDJ8SE

I probably could talk about many others, but I will stop there for the moment.

Okay, here goes.
Final Fantasy X: To Zanarkand:
https://www.youtube.com/watch?v=h-0G_FI61a8
World of Warcraft: Wrath of the Lich King: Arthas, My Son:
https://www.youtube.com/watch?v=86f_U_q4SFg
Skyrim: the whole soundtrack, really, so here's a cool compilation I use when playing D&D:
https://www.youtube.com/watch?v=xWtfo9kuRTU
The Witcher 3: The Trail, but the entire soundtrack is amazing:
https://www.youtube.com/watch?v=s3L0_ez0Dg4
Final Fantasy VI: Terra's Theme:
https://www.youtube.com/watch?v=EHgjRE2rro8
And of course, can't forget the Pokemon music. I like this cover/mix:
https://www.youtube.com/watch?v=N-VvY-3V-dE

the soundtrack from xenoblade chronicles, I'll give a linnk wen i get out of school

Not gonna lie: the first time I ever heard Relm's theme, it made me cry. it didn't help that I was already sad at the time, but still. I find that piece desperately sad, even though it probably isn't supposed to be.

A few of my favourites:

The boss theme from FFX
Big Bridge from FFV
One-Winged Angel from FFVII
BubbleMan's theme from MegaMan 2
Sparkman's Theme from MegaMan 3
Forest theme from Chrono Trigger
Big Boss Theme from Chrono Trigger

But seriously, I have a bunch of the Final Fantasy OSTs and I can just put 'em on random and have a ball. I had a friend of mine through elementary and high school who played through the final fantasy games and Chrono Trigger while narrating/wxplaining what was happening, so I had a lot of exposure to them and loved them dearly. Huge, huge nostalgia, to the extent that sometimes I'll bust out a YouTube speedrun while I'm doing something else because I like the games so much. If there was some way to make, say, Chrono Trigger or Final Fantasy VI accessible, I'd be all over that in a heartbeat.

I completely agree with all of this.    OH I  have novelizations of both games with additional dialog and such. 

Relm's theme, Forever Rachel, and even Rydia's theme from FFIV makes me want to cry,   Heck, since I'm being a crybaby about it,  So does At the Bottom of Night  from Chrono Trigger and Lenna's Theme from FFV.  Maybe it's because I  am so into the series I grow emotionally attached to the characters when I played the games.    But nothing can top Aeris' Death Theme from FF7.   I have an orchestral version of that  from one of the Distant Worlds  albums, and let me tell you.   It's more emotional  than the original.

I think I will do some of your suggestions for some future  enhanced gaming covers.  I did Dr WIly's Castle from Megaman 2.

There's a guy named Wiiguy003 on YouTube who has a whole bunch of 8-bit  stereo video game music, including all the megaman games and almost everything else from the NES.  He provides download links to them.

A few others I did:
Super Metroid: Lower Maridia
https://www.youtube.com/watch?v=PJu4GVl9QLM

Kid Icarus: Underworld (Jazz Orchestral cover)
https://www.youtube.com/watch?v=AowNkd_LijI&t=151s

Megaman 2: Dr Wily's Castle
https://www.youtube.com/watch?v=hVsZWM-AvhU

Legend of Zelda A Link to the Past: Dark WOrld/Death Mountain  Medley
https://www.youtube.com/watch?v=6uvQvxVhYOs

and I'll stop here
Final Fantasy VI: Terra's Awakening Dance Mix
https://www.youtube.com/watch?v=5Z8bJwm9iUk

OK, I am going to come right out and say it.
Thank you very much for making this mod cry in a positive way. Literally. Every single post from post 1 to post 14 is going to be thumbs upped.
After the stuff that's happened there's a sense of positive discussion again, and now this style of topic, wow.
@post 1, do you know which version or soundtrack that final fantasy orchestral main theme is from?
Now, I would like to throw my hat into the ring with some of my own favourite tracks as well.
Super Mario Odyssey: The Odyssey's First Takeoff
https://www.youtube.com/watch?v=y8WxCLkZJiQ
Super Mario Odyssey: Ruined Dragon Appears
https://www.youtube.com/watch?v=6_ELsn1grVc
I can also highly recommend the soundtrack to Bravely Default. I am going to put a few tracks here, because of the way I fell in love with this soundtrack. It needs some explanation which I am going to do with a wall of text first, and then end with the links.
This is an rpg for the 3ds and is like orchestral rock.
The prolog has this really triumphant main theme. However, it's how the character themes
work.
Each character theme plays only when a meter is filled and they are giving buffs, and you've got until the theme finishes to use the buffs. Also each character is represented by a musical instrument in their theme to make them stand out.
It's then what the final boss theme does that's incredible, and for that, you have to listen to the other themes I'm going to put first, and then listen to the final boss theme last. However I highly recommend the whole soundtrack, so much so that it's actually going to be one that I would like to buy on cd.
Bravely Default: Prelude - Moving Toward Hope:
https://www.youtube.com/watch?v=NvoPB7YlkcM
Bravely Default: Tiz's Theme (You are my Hope)
https://www.youtube.com/watch?v=P0Xxnvvykgs
Bravely Default: Agnes's Theme Wind's Direction:
https://www.youtube.com/watch?v=aeVFo15FgPg
Bravely Default: Edea's Theme Baby Bird:
https://www.youtube.com/watch?v=UjQ5aKu123g
Bravely Default: Ringabell's theme Love's Vagrant:
https://www.youtube.com/watch?v=BEgIUiWw42U
and lastly for these, although I'll still put more music after this so keep on going, but, last bravely track is
Bravely Default: Serpent Eating the Ground, or the alternative name is Serpent that eats the Horizon
https://www.youtube.com/watch?v=TPQ1nKZRtaw
But I'm not done yet, although that's the last of Bravely stuff I'm putting here.
SoulCalibur iii: radiant soul (character creation)
https://www.youtube.com/watch?v=CQkDIJ-xrkI
SoulCalibur vi character creation (this one doesn't have a name yet probably because it's so new)
https://www.youtube.com/watch?v=4KpiyQpGLhs
I think that will do for now, although there's plenty more soul series music I could put here too.
I also love stuff like Killer Instinct or Skullgirls and even the smash bros stuff.

No, that’s from the London Symphny Orchestra. They did two videogame compilations. Their Zelda one is pretty great, here it is:
https://youtu.be/MriV_L0Hl5E
And here is Dragon Roost Island done by them:
https://youtu.be/ZUUll4N3u80

Silpheed The lost Planet Stage 1, SEGA CD.
http://www.youtube.com/watch?v=dME8eaYPNp8
That whole soundtrack is pretty awesome.

Stellar Fire (Sega CD) (Intro & Theme Song)
http://www.youtube.com/watch?v=110zNmnIM90
This is actually on the soundtrack, so it counts. The very beginning is the SEGA intro and such, which is not on the soundtrack. The very end is a bit of the main menu music. The introduction itself is narrated by none other than Michael Dorn.

BlazBlue Love So Blue
http://www.youtube.com/watch?v=gulYfd6OFac
Noel Vermillion's theme Bullet Dance from BlazBlue with Japanese vocals sang by Kanako Kondo, Noel's Japanese voice actress.

Bullet Dance II
http://www.youtube.com/watch?v=FwJt7kNuAJ4
A very awesome remix of Noel's theme, introduced in BlazBlue Chrono Phantasma.

Stardust Memory Place of Promise
http://www.youtube.com/watch?v=crwCFXqzJ6I
A very beautiful vocal version of the Stardust Memory song from BlazBlue, once again sang by Kanako Kondo.

There are others, but I'll keep it short for now.

Man I just love the green hills theme from Sonic, and Ryu's theme from street fighter too!
Oh and that theme that plays when Link is on the ocean in Fantom Hourglass, as well as the title screen theme are both amazing.

I've been on a major touhou kick recently. Touhou is a series of bullet hell shooters that have been produced since the mid 90s with  ZUN being the  only designer, programmer, artist, and composer.
https://en.wikipedia.org/wiki/Touhou_Project
Some music from the PC98
https://en.wikipedia.org/wiki/PC-9800_series
era and related  Seihou Project was posted earlier in the thread, but here are some I personally like from the windows era.

Embodiment of Scarlet Devil:
Stage 1: A Soul as Red as a Ground Cherry:
https://www.youtube.com/watch?v=dYvvKyYIc5s
Stage 1 boss:   Rumia's Theme - apparitions Stalk the Night
https://www.youtube.com/watch?v=fd8IHH4Tz20
Stage 4 Boss:  Patchouli Knowledge's Theme: Locked Girl ~ The Girl's Secret  Room
https://www.youtube.com/watch?v=ygyraTutBJg
Stage 5 Boss: Sakuya Izayoi's Theme: Lunar Clock ~ Luna Dial -
https://www.youtube.com/watch?v=01skyPMeeoc
And more well known;
Stage 6 Boss: Remilia Scarlet's Theme - Septette for the Dead Princess
https://www.youtube.com/watch?v=aJQ5HsXlPTo
Extra Stage Boss: Flandre Scarlet's Theme - U.N. Owen was Her?
https://www.youtube.com/watch?v=w63mKJB5ZJQ
Perfect Cherry Blossom:
Stage 3 Boss: Alice Margatroid's Theme - Doll Judgment
https://www.youtube.com/watch?v=Gha7mck … p;index=25
Extra Stage Boss: Ran Yakumo's Theme - A Maiden's Illusionary Funeral ~ Necro-Fantasy
https://www.youtube.com/watch?v=ewGbGpEp-dM
Phantasm Stage Boss: Yukari Yakumo's Theme - Necrofantasia -
https://www.youtube.com/watch?v=2vjZ1SPAH6g
Imperishable Night:
The two main player characters were bosses in this game and had awesome themes:
Stage 4 (uncanny) Boss: Reimu Hakurei's Theme - Maiden's Capriccio ~ Dream Battle
https://www.youtube.com/watch?v=bBde0Kz-Bcc
Stage 4 (powerful) Boss: Marisa Kirisame's Theme - Love-colored Master Spark
https://www.youtube.com/watch?v=_6L6E7TLy10
Extra Stage Boss: Fujiwara no Mokou's Theme - Reach for the Moon, Immortal Smoke
https://www.youtube.com/watch?v=S-usbNcDD9g
Mountain of Faith:
Stage 5 Boss:  Sanae Kochiya's Theme - Faith is for the Transient People
https://www.youtube.com/watch?v=q4gqGhN0xnE
Subterranean Animism
Stage 6 Boss: Utsuho Reiuji's Theme - Solar Sect of Mystic Wisdom ~ Nuclear Fusion
https://www.youtube.com/watch?v=Xy_-7OXophY

ZUN is pretty hands off when it comes to Touhou fanworks which means that there are thousands  of remixes in any genre you can think of. This folk/Irish-ish version of U.N. Owen was Her?:
https://www.youtube.com/watch?v=dWPv3TNcuOk
and this western version of Faith is for the Transient People:
https://www.youtube.com/watch?v=HEwdLH1MBU0
are good examples of that. Some of my favorite remixes:
Vocal U.N. Owen was Her?
https://www.youtube.com/watch?v=xOz-T3NPtLA
Magnum Opus is generally pretty good if you like metal/power metal. Here's Love Colored Master Spark:
https://www.youtube.com/watch?v=rLCwS0o_cF4
and Necrofantasia:
https://www.youtube.com/watch?v=G6AV-7fK6TM
And for something completely different, a vocal cover of Doll Judgement by Iosys
https://www.youtube.com/watch?v=1pDM6fQUfJs
Enjoy.