I could never decide on just three...

Starcraft has a very ambient soundtrack, and it's still epic.

Portal's soundtrack is very good, and not only the ending song.

The Curse of monkey island 3 has an amazing soundtrack as well.

The only one I'm sure is on the list is the soundtrack to The bards tale. It's hilarious, catchy and fits the game like a glove.

The soundtrack in Bloodlines is also awesome, and so is the one in Penumbra episode 1.

There's so many gems to choose from, but for my top 3 I'd have to pick:

Chrono Cross
Castlevania: Symphony of the Night
Xenogears

Honourable mentions to the Metal Gear series (pretty much any of 'em really), Parasite Eve, FFVIII (even though I absolutely detested the game) and Zone of the Enders the 2nd Runner.

Deus Ex
Mass Effect
Myst <- I remember paying for that one back when the game first came out.

Morrowind
Zelda: OoT (especially Kakariko Village <3)
Megaman 3

The Bandit:
I can't believe people are mentioning modern Sonic games... It's just nasty, skank rock. : /

Though I didn't notice it until my most recent playthrough, Half-Life 2 really had some great music thrown in. The original Halo music was better than Halo 2, but Halo 2 was decent.

With Halo, I'm taking the literal sense of soundtrack, the CD soundtracks. Halo 2 had much more, including "Never Surrender", which is just epic.

1. Eternal Sonata
2. Valkyrie Profile 2
3. Golden Sun

Sakuraba FTW!

(oh, and kudos for the one who mentioned Dark Cloud 2, although some themes *cough*main town theme*cough* ruined the whole experience for me)

Oh, you've got me started on this!

I'm an avid soundtrack listener, as I try getting tons of soundtracks for the games I love. over 400 tracks on my iPod are soundtrack, no joke. I simply CANNOT limit myself to my top 3.

StarCraft had an 'okay' soundtrack. I'm not criticizing it on the oldness of it, and the use of MIDI.

Red Alert, Red Alert 2, and Yuri's Revenge. I'll go as far to say Universe at War. Why? All of the soundtracks were composed by the exalted Frank Klepacki. Even he used a bit of MIDI in his music. But he did it in such a hard-rocking, bad-ass way that his music simply cannot be overlooked. He doesn't just do the prototypical '90s music, either: in UAW, he does some epic suites for Masari and even the Heirarchy.

Supreme Commander. Jeremy and Julian Soule do a soundtrack of epic proportions here. SupCom has one of the most epic, bombastic (in a good way), rich, and dynamic soundtracks I've ever heard; and I've heard many. The SupCom main theme is used in such a way, you believe it belongs there, not forced in like other soundtracks. (Mass Effect being one of them.) The diversity between factions reflects upon the music, and you have a definite feel for each of them within the music.

Medal of Honor: European Assault. When I first learned that Christopher Lennertz was taking over as the composer for the Medal of Honor series, I braced myself for the absolute worse. And guess what? I was blown away. Right from the beginning of the soundtrack, you don't hear jingoism or patriotism. You hear a unilaterally understood theme of loss, risk, and victory. Dogs of War (initial track) literally brought tears to my eyes. This is a deep soundtrack, while lacking a bit of diversity, as this is a WWII game. It's jsut done with such care and detail, I can not afford to overlook this classic.

Halo 3. I thought I was going to be fed the same crap again, but Marty O'Donnel actually stepped up to the plate, and created a decent soundtrack, featuring more elegant themes and challenging the commonly held idea that piano doesn't belong in a shooter. All I can say is WRONG!

Super Mario Galaxy. I know everyone's going to hate me for this one, but Nintendo's composers (including Mahito Yokota) gave it their all when composing for this game. IF there ever was a benchmark for diversity, this would be it. SMG's soundtrack is one of the most refreshing soundtracks I've heard in a while, forgoing a ham-handed effort at a soundtrack like most developers do, you here elements that are inexplicably right, even though you'd never think there was this or that in the music; it just fits. Tracks ranging from the epic opening to the heart-felt closing, to the fun, vibrant tracks in between, this is a soundtrack to be remembered.

Command & Conquer 3. When Franck Klepacki was off composing with his buddies over at Petroglyph (which composed of former Westwood members), EA needed someone who could fill his shoes for C&C3. I know EA probably wasn't expecting to get such a soundtrack out of Steve Jablonsky (and Trevor Morris), but he went above and beyond their expectations, composing one of the finest electronic albums I've heard.

I'll end my ranting with some others, and honorable mentions:

Star Wars: Republic Commando (Kothe!!! Ratande kothe!!!)
Command & Conquer: Generals (Zero Hour)
Sins of a Solar Empire
Battlefield 2142
Select tracks from LoZ:OoT, WW, and TP
Medal of Honor: Frontlines
SimCity 4 (just breathtaking)

haruvister:
The Chaos Engine must get a mention not simply for being the best of The Bitmap Brothers' brilliant techno compositions, but also for the fact that it was the first context-sensitive score I can think of.

Kudos for mentioning The Bitmap Brothers! My fav work of theirs was using Megablast by Bomb The Bass as the soundtrack to Xenon 2. I cranked that baby up.

My three favorite soundtracks would be:

1) Star Wars: KotOR
2) Fable (a brilliant Danny Elfman score)
3) Bioshock

1) Illusion Of Time (SNES)
2) Zombies Ate My Neighbours (SNES/Megadrive, but obviously SNES sounded a lot better)
3) Sonic 2 (Megadrive), in particular the second zone.

Why I felt the need to put the game system in brackets when I'm posting in a gaming forum I don't know.

In my old band we did a medley of Zombies Ate My Neighbours songs and it was the absolute tits! No one got it though :(

Streets of Rage 2 - Easily my favoritestest game soundtrack evep. Yuzo Koshiro is brilliant.
Rez - But it's more than just the soundtrack itself. It's what it does with the music.
Jet Set Radio - Not since ToeJam & Earl has a game been so beautifully funky.

Khell_Sennet:

With Halo, I'm taking the literal sense of soundtrack, the CD soundtracks. Halo 2 had much more, including "Never Surrender", which is just epic.

I love Halo dance music (unce unce unce)

Final Fantasy VII
Command and Conquer (the Original game)
Chrono Trigger

Smash Brothers
Ocarina of Time (or any zelda for that matter)
Final fantasy VII

Rob Sharona:
1) Illusion Of Time (SNES)

That game ruled !

The feel of that game is something else. And that section where you are stuck on that raft is brilliant. Funny bit to like most but still :P

1. Zone of the enders the second runner
2. Bioshock
3. Sonic 4 death egg theme song (way ahead of its time)

klarax:

The feel of that game is something else. And that section where you are stuck on that raft is brilliant. Funny bit to like most but still :P

Yeah that bit is ace. So dramatic. I love it when you have to fish to survive.
The music in that game is amazing.

Final Fantasy VII and Castlvania: Symphony of the Night both had great music that fitted the atmosphere and can still be remembered to date. Also GTA 3. It counts because nearly all the music was made especially for the game.

and i'd kill myself if i didn't mention the main theme from Metal Gear Solid

Smash Bros Brawl is my numero uno, the music library is literally a cross-section of Nintendo's best tracks.
After Brawl would be Wind Waker, for the Sailing theme, Molgera's theme, the credits music, all of it.
My third favourite is probably Metroid Prime's tracks. Beautifully atmospheric and nostalgic.

My spinal cord would probably throttle me in rage if I neglected to mention Still Alive and the battle themes from Riviera. Truly epic, those songs.

I my opinion the Final Fantsy ha d agood line of soundtracks as well as other good games such as Halo and gears of war

GTA III
Zelda Series
Fable

Silent Hill
Half Life 2
Halo
(I realise there are more than one sountrack for SH and Halo, but the entire series has a good soundtrack)

Silent hill 2
Mario galaxy
Final fantasy 8.....yeah i said it!

Call of Duty
The score to Resident Evil: Outbreak File #2

And this is going to sound odd but
Lego Rock Raiders for the PC
It's an old RTS that was used to promote a Lego toy series, but really wasn't a child's game.

Anyways, I ripped the three six minute tracks looped in the game and whatever studio pieced them(I have this odd feeling it was Gray Matter) had a good thing going because I absolutely love them.

The soundtrack comes on the game disk and though it definitely doesn't out-do any recent soundtracks, I think it's worth noting.

In no particular order:
Halo 3
Bioshock
Mass Effect

Though, I have been known to variate depending on my mood or just my interest at the time.

half life 2
excite truck (kudos if you get that)
space invaders

exocel:
Final fantasy 8.....yeah i said it!

Nothing to be ashamed about seeing as Final Fantasy VIII has the best Final Fantasy soundtrack of all time.

GTA Vice City. I have never once downloaded a video game soundtrack before then. All 7 albums. with DJ banter.

Of course, that's not really an original score.

Runners up: Halo series, Xenogears.

Don't really notice the music really, if it suits the atmosphere and situation then it's good but I can't say I'd find it memorable. Can only mention intro/outro songs.

Fallout 2
Fallout 1 (I mean the Ink Spots and Louis Armstrong ones - both really set the alternate history era, scene and hopeless lamentation and regret of the whole thing for me.)
Portal (Still Alive - really got me smiling at the time, still does actually, but have only listened to it twice).

1)GTA:SA (although they are all good)
2)Icewind Dale
3)Morrowind (Liked it better than Oblivion for the most part)

1)Xenosaga 3 Honestly just incredible. Not only do the pieces complement the parts of the game where they are played amazingly well they are really good enough to be worth listening too if you haven't even played the game.
2)Final Fantasy 8 Same as above but on a lesser scale.
3)No other game I've played can really compare to these two in my opinion so I'll just throw in general Final Fantasy here since they usually have better quality then most.

Morrowind (Epic loop that gets you carried away)
Red alert 2 (HELL MARCH!!!)
Metal Gear Solid (I love the music, it suits every aspect of the game so good)

For me it's;

1. Shin Megami Tensei: Digital Devil Saga 1 & 2
2. Final Fantasy VIII
3. Initial D: Arcade Stage Version 3

Metal gear here aswell, not only great, but in MGS4...

it comes on an in-game ipod!

now thats handy.

3.Megaman 2
2.Final Fantasy VII
1.Katamari (All games, though damacy soundtrack is probably the best.)

1. The Halo series
2. Half-Life 2
3. Final Fantasy series (because of their use of a few songs throughout every game)