Warning, this will be long because Earthdawn was my drug of choice for many a year (and always threatens to come back
). I’ll try to piggyback on other responses to not repeat too much.
If I wanted to sum up why Earthdawn is awesome in a single word, it would be flavor. That should come through below.
I personally like that the racial mix is different from standard fantasy without having too many or departing far from normal fantasy tropes (in addition to humans, elves, and dwarves, there are trolls, small winged fairies, rock men, and lizardmen as major races).
And orcs! Oh, and if you have a mental image of what these races might be like based on previous experiences, you might be surprised. The lizardmen (called t’skrang) are river dwelling traders and pirates with a strong swashbuckler feel to their culture. The rockmen (called obsidimen) are literally made of rock and “emerge” from a magical liferock instead of being born in a conventional sense, and they’re so bulky that their written language is basically landscaping (or they hire a scribe). The trolls are not the green monstrous kind from DnD, but rather resemble huge cousins of orcs with large horns. Oh, and they’re known for sailing the skies in their airships and using magic to literally leap off the side to descend on a small village to raid it.
There is a well developed villain (the Theran Empire and their slavers) that is not completely evil.
The Therans are just one of many well developed threats to toss at the PCs. But I think the most important are the Horrors, abominations from another realm of existence (astral space) that are about as Lovecraftian as you can get. They vary widely in power level, with the more powerful ones finding sustenance by causing strife, misery, fear, etc. Many of them can corrupt the minds of their victims in all sorts of insidious ways. Horrors get top billing for me because the backdrop for Earthdawn exists solely because of the damage they dealt to the world…
In Earthdawn (and Shadowrun), the level of magic on Earth ebbs and flows, like a sine curve. When the level of magic gets high enough, the walls between Earth and astral space get thin, and the monsters that live in astral space (the Horrors) can come to Earth. Earthdawn is set just after the end of what’s called the Scourge, a 1000 (I think it was this long) year period in which Horrors ravaged the world. During that time, the peoples of the world hid in underground cities called kaers in hopes to survive the Scourge. Not all succeeded. So basically, you have a world with a magic level that’s low enough that most of the Horrors have went back to astral space (but certainly not all); plenty of excuses for dungeon crawls thanks to the kaers, and all sorts of other goodness.
Spells used matrices to cast safely, although you could risk casting a spell without one. Each spell had a number of needed Threads to cast it. From as few as zero and increasing as the power of the spell increased. More experienced casters had matrices that could hold more than one thread at once. Casters would prepare their available matrices with spell usually during a short rest and once loaded could continue casting the same spell repeatedly.
And the cool thing is these spellcasting rules had flavor explanations behind them. Since spellcasting draws power from astral space, casters had to use matrices to protect themselves from the corruption in astral space from the recent activity of the Horrors, not to mention to try to hide their activity so a Horror wouldn’t decide to pay a visit. Furthermore, only so much of a spell could be stored in a matrix, so the caster had to weave additional magic threads into more complex spells in order to cast them.
Anything but minor Magic items couldn't be used unless the character attached a Thread to the item (same Thread as mentioned above, non-casters did not receive the Thread Weaving talent until 4th level). As they went up in level they could strengthen their thread and increase the power of the item. Sometimes it required additional knowledge or deeds before you could strengthen your thread.
Magic in Earthdawn runs off the basic principle that (a) everything had a “pattern” or mystical representation of itself and (b) to access magic you could weave threads to such patterns. So to use a magic item, you had to weave threads to it (there’s that rules baked with flavor again!). And if you wanted to weave threads to something, you needed to know about that something in order to do it. And the stronger the thread, the greater the power. So for a weapon, you might need to learn it’s name, then the name of the person who forged it, then where they forged it, then what beast the creator killed with the weapon, and so on.
Each Discipline has a number of Discipline Talents (abilities all characters of that Discipline must have) and Talent options (which allows for diversity between members of the same Discipline). Among other things, as characters advance in Circle, they gain new Talents, new Abilities, and bonuses to their Defenses (Physical, Mental, and Social), bonuses to Initiative, Recovery Bonuses (the equivalent in 4th Edition of gaining additional Healing Surges).
Actually, a lot of Earthdawn tracks to 4th Edition DnD. Talents feel like powers. All attacks roll against a defense score. And so on. I really wouldn’t be surprised if the 4e designers looked at Earthdawn for inspiration.
To advance, a character earns "Legend Points", and keeps track of the total that they have earned, and the current number they have to spend. Legend Points are spent to raise attributes, learn new talents, upgrade old talents, learn new skills, upgrade skills, learn spells, and purchase Karma points.
What’s cool about having legend points vs. XP is how it really makes xp feel like it has a tangible in game effect. There’s literally a table that shows how well known/famous a character is based on his/her legend point total. One of the shticks of Earthdawn is that the characters are “building their legend.” Defeating opponents earns you legend points, naturally, as does turning in certain trophies (of course your legend improves if you show off the fangs of a hydra you killed to the nearby town). Oh, and you can write a journal and hand it into the Library to earn a handful of legend points
Bah, I could go on and on, but I think I'll shut up for now
Happy to talk about any of it more.
