I approve of this thread!
Well, I would had added the European/Japanese game of the console, though.
And this type of threads needs more than simply lists. Lists don't do your opinion on a game justice.
What you need to do is to entice folks interest in a game -or more than one, if you have the time- by doing a nice and completely biased reviews, no need to be fair with old classics, it's all about exaggeration, hyperboles and superlatives used to describe the unaltered awesomeness of a classic.
Of course, most old games didn't age well, but that's not these type of threads are about, they're about hyping old games and create a growing interest in people that will climax with them chasing down the said game (with any mean necessary!).
And to do that, one needs pictures, lots of them, to accompany his/her quick review!
I'll start right away myself and do what I preach:
The Story of Thor (EU/JP) Beyond the Oasis (NA)
It's an awesome top-down action adventure title, back in the days some journos would refer at it as an action RPG, but in fact it's not more an ARPG than Zelda.
It has been developed by Ancient, a not so famous japanese dev house, which also co-deved a nice little RPG on the SNES called Robotrek by the way. Their chef d'oeuvre remains The Story of Thor 2 for the Saturn. Game that is beyond awesome (pun attended) but doesn't run on Megadrive, so I'll keep any positive stuff about it for later.
Perhaps due to the fact that the game came late in the Megadrive life or to the quality of Ancient art team, the graphic quality of this game is incredible, especially when you know the technical limitations of the Megadrive, it supported all the nifty effect and hacks one could expect from the machine (I can't remember if it faked transparency, or not, though) and all that came in 24Mega (bits) cart (!), it was so worth of note that the European version of the game had a red sticker with "24 mega" plastered on it.
The US version of the game also had a sticker, it said "the largest adventure game on genesis", nothing less. Now, was it it the largest adventure game on Genesis at that time, that I don't know. But what I know is that the game had a indeed a large gameworld and a long adventure.
I might give you a detailed lowdown on the gameplay, but I won't. I think that everybody should grab this game and give it a fair try. There's no reasons to hate, for it is awesome (yeah, I know I already said it), nonetheless, thoses who had played Story of Thor 2 might have been spoiled by the fact that the sequel is a Story of Thor X100, with better controls, deeper gameplay elements, richer graphics, smoother animations and such. All you need to get back to Story of Thor is give the game some time, after a short while you should do with its small technical shortcomings.
Now, enough talk, take a look at a few of these shots, and then start hunting a version of the game!
Here's the horrendous cover of the US version of the game (The person responsible for the name change and the cover needs to be dragged outside and beaten to a pulp, if it has not not already be done)
The game had a cool and quite quick intro, thing that we might never imagine for a modern adventure game, heh (the quite quick intro part).