[Tyhm]

It seems like unique races are doomed to constantly run into the problem of Double the Work for Half the Reward. It's the same dillema that the Multi-Branch RPGs ran into:
Your programmer makes a game with 100 hours of plot. It takes him 10 months (let's say it takes a month to make 10 hours worth of game, working solo).
The gamers play a game with 100 hours of plot. It takes them 100 hours to play.
Your programmer makes a game with 10 major branches, each leading to a different ending, each of which leads to 100 hours worth of game time. It takes him 100 months to make this game, working solo.
The gamers play a game with 100 hours of plot. It takes them 100 hours to play.

Same problem with races. Say I make a server with 100 quests, each of which assumes the player's a human with a sword and a shield and the ability to ride horses. It takes me a year, even with a full team of programmers I can trust explicitly. Then I make 5 races, none of which can do the same quests. Now it takes me 5 years to make a server with 500 quests, and each player only gets to see 100 of them. And it requires either 5 times as much staff or it takes 5 times as long to maintain anything.

The only solution I ever found was to make the quests such that any race can do them just as easily...which proved problematic. I mean, how does a Zorbi take on a boulder-belching sphynx? Throw bubbles at it and hope they do as much damage as a hammer or a sword or an alien ray-gun?

Probably the perfect solution will be to make quests that fork only briefly, like a river splitting around an island. All 5 races enter Graal Castle. At some point they have to cut a rope to drop a bridge to get to the next room. The human and vampire can slash the rope holding the drawbridge closed to get out. The gnome hammers the stake the rope's tied to, dropping the drawbridge, to get out. The alien has to focus his beam on the bolt at the other end of the rope until it melts. The zorbi has to bubble the torch by the door and float it into the rope to burn it to drop the bridge. All 5 races proceed to the next room, though you had to script 4 different ways to bypass the bridge. It ain't perfect, but it beats the alternatives.