I'll list a few to get this topic going:

- Insector X
- Music From Jesus ~ The Fearful Bio Monster
- Bible Master 2

Perhaps these aren't all that obscure, but bear with me

OK, I'll bite:

- The Legend of Dragon Slayers
- Game Sound Nichibutsu -G.S.M. Nichibutsu 1-
- AlsharK
- Phantasie RPG Amaranth
- Devil Crash/Alien Crush
- Takeda Shingen

I'd say the Rockman X arrange even though I'm not really into jazz.

I checked out the soundtrack to the Sega CD game Tenbu when I was on a quest to discover everything Wolfteam/Telenet related. It wasn't what I had hoped (no super-busy Sakuraba bass and melody, no saccharine sweet Shiono tunes) or even really much like anything I usually think of when I hear "game music". I kept listening to it though, and haven't heard anything else much like it.

Rockman X qualifies as obscure now!?

On-topic: Johnny Bazookatone.
The album only came with the PC version of the game, which no one bought because the game was kinda ASS, but the soundtrack is really great, actually. Nice if you love jazz, lounge, rock and blues and that kind of stuff.

Rockman X qualifies as jazz now?!

It's not like it's growing on trees; really depends of your definition of "obsure." In the future I think we need clarification.

I don't know, I've always considered it kind of jazzy.

Rare and obscure are not the same things.

Can't argue with it being jazzy though.
What would YOU call it, Smeg?

I was teasing a bit, but fusion really isn't what comes to my mind when I think of what "jazz" sounds like to me.

Close enough. I mean albums falling into either category are going to cost you a pretty penny.

Not necessarily. An obscure album is less likely to be in high demand, regardless of its rarity.

[edit] uh, also I didn't say what you're quoting as me

A rare album can be known or obscure. Usually they are rare because they are in demand. Game Music Graffiti and Phantasy Star Sound Collections are well known in the game music community, but physical copies are few and far between.

An obscure album is more likely easy to find if you were to know to look for it because of lack competition. Usually I think of obscure albums as ones bought/downloaded on a whim or by maybe because of one person that recommends it, but no one else is really familiar with. Being around the VGM scene for nearly 14 years, good albums fade from obscurity quickly once they are discovered/shared.

Anyway, a couple picks from me:

-Fist (a cool synth-pop fighting game arranged soundtrack...It sounds like Tokimeki Memorial music done for a fighting game)

-Burai Prototype (an arranged album by the all-female metal band Show-ya)

-Waku Puyo Dungeon (an early impulse/cheap purchase of mine, it's a cool bouncy and upbeat dungeon crawler OST)

-Cotton 100% Arranged Album (a staple of mine. Fun melodies arranged in a cool rock/synthpop style)

-Sailor Moon S Game Music (how many people actually know the Sailor Moon and Dragonball/Dragonball Z soundtracks released for the Super Famicom games are actually really cool arranged albums? Out of both camps, this one has been a long standing favorite and a staple of my collection. Also of note: Dragonball Z Butouden 1. Credit goes to Jodo for originally cracking the mystery of the DBZ albums.)

-Vimana/Teki Paki (bought from Miker, but originally downloaded on a whim. Toaplan music is really obscure and unknown, but I love their sense of melody and killer arcade synth programming)

-Konami Famicom Memorial Best albums (I only have Vol. 1 and Vol. 3, but they prove that Konami simply owned the NES era. Alongside Capcom of course. All too often, I get something from one of these albums on random play and it's a killer tune. The audiophile in me loves these recordings...I didn't know NES/Famicom music could sound this rich and exciting.).

-Megami Tensei I and II (Shoutouts to Strohmie for discovering this one way before Megaten was discovered by most of the western world and also for discovering one of Ryo Yonemitsu's best non-Falcom works in a time long before vgmdb.)

-Blue Almanac (an arranged album by Iwadare and friends, same ones that did the Langrisser 2 Original Game Music. Kinda early Phantasy Star-ish, not terribly exciting, but quirky and fun. Glad I've held onto it all these years).

Götzendiener. Blue Almanac is also a good pick.

Was going to list Gotzendeiner myself! Here are some of my recent findings, though I'd never be able to choose any definitive favorites from the vast and expanding list of obscure material:

-Gungriffon Original Soundtrack
-Artdink 10th Anniversary
-Space Manbow
-Tail of the Sun
-E.D.F.
-Alien Soldier

Just a few. Can't think of that many more at the moment, nor have I listened to the majority of albums I've put down on my review catalog.