As I have stated the product was originally released through Fasa and was well maintained until the companies collapse. Shortly after words the line was picked up by Living Room Games. Living room games produced a second edition of the game which was pretty limited in the change scope. Complicating issues the product was Also tackled by Austrailia's Red Brick LLC. Red Brick released a line called Classic for some time and then switched over to a third edition line. At present I am unsure of what the folks at Red Brick are doing. I see products for Paizo's Pathfinder and Pinnacles Savage Worlds, what I don't see is Earthdawn mechanics products. You can find them offered at heavy discount through Mongoose publishing though. I know they had a relationship with the Mongoose people and that it has now ended, I just don't know what that means for future Earth Dawn product.
Speaking more myself, I only played the Fasa material. In this post I think its best I stick to what I know. I would love it if someone could educate us about the second and third edition changes, but for now I am sticking with first.
The first edition of the game takes place in a distant pre history of earth. Physically the locations pretty similar to the real world Caucasus mountains and Urals. Much of the game focuses on tribal people retaking the land after a magical catastrophe. I know the third edition has expanded to include material for several other areas but first edition was primarily the area around Macedonia and the black sea.
Certain mechanical and story factors made the game pretty appealing especially compared to much of the Fantasy that was out at the time. Back in first and second edition AD&D the elf was pretty powerful, to the point where many took them by default. Earthdawn present humans in that mechanical sweet spot, making them desirable. Tacking onto the No Elves thing, was the fact that elves were presented a little more fucked over than in standard Tolkienesq fantasy. Normally elves are good and great and beautiful. They live forever and are Eco friendly and just so sweet it makes your teeth hurt. Earthdawn makes the elven high court horrible and dark, if a little too gothy. They have thorn vines living inside their bodies and bursting from their skin. The Elven queen may be horror possessed and from a general stats prospective you have to be focusing on dexterity to consider taking them. This I like, it turns something saccharin and annoying into something with a touch of edge and enough role playing meat to be interesting.
Mechanically Earthdawn is a joy, really a joy. If you work into the system and start reverse engineering it, you will find its all constructed upon very solid principles. They set the experience reward system so just being there has a base line of rewarding the player every three sessions. The rest is calculations from there, but it shows they were starting from a philosophical idea of constant advancement even for the sit there like a lumpeyest player. The open ended dice the system uses are beautiful. Seriously you never see a party explode with excitement like you do when someone goes off in Earthdawn. Its a bit hard as a GM that any player can walk up and destroy your favorite big baddy but it sure has the players jumping in their seats. I can remember rolling well over 80 with a D4 and a D20 re rolling when the dice maxed out. The table was full of shouts every time I hit max on a die. That sort of thing just makes the evening come alive for players.
The horrors are another solid component to the game. Think of Lovecraftean horror added to a fantasy game. These guys are just goofy powerful and very unnerving in how they work. They are there to corrupt people. Some are mindless killer but the worse work more slowly. The best part about it is they have stat blocks. You can see how bad they are and they are bad. The hunter of dragons has Raid level stats that I am unsure even a max power group could handle. Most games leave the stats out for things these days, if they want to say its too powerful to kill. here they wrote out the states and then multiplied them by 100. I like that idea of coming up with the point of max achievement and then setting a big baddy well beyond those abilities, its give players something to shoot for. Give them something to fail at.
As a new GM you are going to need the Earthdawn Rule book as well as the earthdawn companion. These two books cover the game system and allow characters to advance to 15th circle which is the game max. You may consider the Arcane Mysteries of Barsaive as another expansion book, but one more generally for all circles of advancement. Creatures of Barsaive is the monster book, Horrors is the nasty monsters book. From here you will often find that the crunchy game material is inserted into more fluffy books. This is as opposed to the modern splat book approach which is pretty crunchy stuff all in one book. I sort of like this idea as your player may read the fluff and actually have some role playing around the character they have just created. They will understand what a Horror is and why their new Horror Hunter is adding threads into them. Knowing how the blood wood works may make your new blood elf character come off as less a goth douche and more of a real person.
For all the goods of earthdawn there are some factors you should be aware of. The game works on the idea that characters are following a mystical path which is their class. Their is pretty limited variations in these paths, and they end up being almost an arch type at the very high levels of the game. Its not first edition AD&D where ever fighter is the same, but you are a well defined character. If you are looking for a game that allows for heavy personalization like some of the skill based games, this may not be for you. If you are looking for a hybrid character type, again this may not be for you. The path to power comes from working your way up the circles. Working on other skills may limit your rise. This is similar to how multi classing can work against casters in 3rd. edition D&D but it effect every class in Earthdawn. Also your high fantasy ideas may or may not be well suited to Earthdawn, something like a Knight in shinning armor feels very out of place with my idea of earthdawn. A roman or a Greek warrior could fit in but as a villain from Thera.
All and all this is a great game. You can pick it up off eBay with some work. Go to mongoose for the third edition. Or wait on Red Brick LLC to reprint stuff. Its a lot of fun and is well supported, if you work at it. Its also pretty unique.