Well there's this guy called  smilerfrog who had a journal about it and I thought why not make a reply in a way. Journal of the source is over here - http://www.furaffinity.net/journal/1636408 - so have a looksee at a guy's excellent taste in game music while I put down mine in no discernible order.

I actually do have a video on my Youtube account (FinalGamerJames) that shows my 13 favourite videogame music themes of all time, but I will not link it here for two reasons.
Firstly, I've changed in what music I like more or less.....mostly.
Secondly, I want you to savour the songs in all of their entirety.

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1. Main Theme of Jungle Strike - http://www.youtube.com/watch?v=ovCoKUdwn78
Ever since I can remember, I loved this theme. It has a strange nostalgia to it more than any other game music piece and it remains always my favourite videogame music piece of all time for its adventurous spirit. It really makes me think I can do anything!

2. Kimera II (G-Darius) - http://www.youtube.com/watch?v=HOYvqr2yZEs
What has become my favourite Playstation song ever from a game I never even played, Kimera II is a mind-bending experience of a song that takes me away from reality briefly in its hauntingly electronic but spiritual melody that seems to dive deep into the recesses of my mind.

3. Forest Temple (Legend of Zelda: Ocarina of Time) - http://www.youtube.com/watch?v=du1LZPZVwy8
Another haunting melody that chills me to the soul by its strange false sense of deja vu that it gives me when I hear it. The warped strings, the strange chorus that comes in halfway to the forefront of the melody, it all brings a sense of abandoned nostalgia, truly of a place long abandoned, a place of memories that nobody will ever remember.

4. Funky Dealer (Jet Set Radio Future) - http://www.youtube.com/watch?v=H2ScC49tllU
If you play this song, I will dance without warning.
I am not kidding.

5. Howl of the Departed (Lost Odyssey) - http://www.youtube.com/watch?v=2AWsrBlB9hI
This is quite honestly my favourite boss theme of all time now. This beats One-Winged Angel in every single way (and no that song was not my favourite boss theme before this one even if it was quite good).
It's more dramatic, has a greater use of choir, and is far more insanely epic rhythm-wise than Uematsu's previously known opus. I just cannot feel un-epic when listening to this song, it's MAGNIFICENT.

6. Mickey and the Beanstalk (Mickey Mania Sega CD) - http://www.youtube.com/watch?v=rOj1dapvoMs
One of the first projects of award-winning movie composer Michael Giacchino, this classical reinterpretation of my favourite song from Mickey Mania is just mind-blowingly beautiful to me. It plays and spins so whimsically like a ballet dancer to perfectly bring that image of an adventurer jumping and dashing amongst the clouds and beanstalks.

7. Convulsive Madness (No More Heroes 2: Desperate Struggle) - http://www.youtube.com/watch?v=nGuEgHH2OI4
I haven't even played this game yet and I already love the soundtrack to this, ESPECIALLY this one which for spoiler reasons to myself I know only as Convulsive Madness, and as phase 2 of the final boss.
Jesus christ this is an insane boss theme, it's pure madness, it makes me fear the psycho who wields this theme, wild-eyed and unable to give a goddamn FUCK about what's gonna happen to you.

8. Theme of International Karate - http://www.youtube.com/watch?v=jzlK_JNuOGE
Now THIS is old school. The simplistic oriental vibe of this pure 8-bit song is just wonderful. It sums up patience, dedication, persistance and strategy, all of which are required not only in martial arts, but also in becoming a true gamer back in those days when challenges were greater within simpler boundaries.

9. The Moon (DuckTales) - http://www.youtube.com/watch?v=G_80PQ543rM
Someone on ScrewAttack forums once said that this theme perfectly represented the 8-bit era. I completely agree. A slow uncertain start, slowly rising into a glorious pitch of bountiful energy and pure joy that just never stops. It's perhaps the most anthemic 8-bit song for how it represents the best of that era.

10. Mods de Chocobo (Final Fantasy VIII) - http://www.youtube.com/watch?v=XF-w0FW5hbA
This is, without a doubt, my all-time favourite Final Fantasy theme. Ever. Firstly it's a reimagining of one of the few songs that has been through most of the series. Secondly, it is the BEST reimagining for being a rock ballad of the Chocobo song. Regardless on how I feel about the game itself, this song right here will always get me into an adventurous mood ready to kick ass and take the reins into a whole new continent.

11. Metropolis Zone (Sonic the Hedgehog 2) - http://www.youtube.com/watch?v=yRuJfhEeCe8
I'm probably one of the few people who enjoy this level and its theme. Despite its frustrating nature of irritating starfish enemies and odd screw-elevators, this has such a goddamn awesome song, a ripping 80s-feeling rhythm complete with robotic vibe that sums up this technological tower of Babel well for me.

12. Intro of Zelda II: The Adventure of Link - http://www.youtube.com/watch?v=UiETgEHcbTQ
This is pure nostalgia to me, similar to the Jungle Stike theme's reason of being in this list for me, but in a softer more soothing way. This was the song that made me realise truly that an adventure was always waiting for me in another world, entirely constructed of pixels and coding, and all I had to do was to press Start. Even if DuckTales was the first game I ever played, this song brought to me my first sense of adventure.

13. Title Screen of Pokémon Gold/Silver - http://www.youtube.com/watch?v=eXrW.....eature=related
Yet another theme that brings to me the spirit of adventure and hope. Despite my absolute love to the remake's magnificent soundtrack, there's a few songs that I still love the original versions of, such as this one. As soon as that legendary winged beast appears, the Game Boy just pours all of its heart into making this song, resonating with such a pure will that it's impossible to not love, all with a wonderful variation of one of the most memorable themes of my generation.