Plane Shift

A free MMORPG based on the open source "Crystal Space" engine. It takes place in the underground realm of Yliakum, encased within a gigantic stalactite. The game is unfinished- current players are also testers of the game, and many of the game mechanics don't work. Roleplay is encouraged, particularly since a lot of the other stuff isn't very exciting at the moment.

This game provides examples of:

Absurdly Spacious Sewer (The sewers beneath Hydlaa. There's a whole cult living down there!)
Beneath the Earth
Call a Smeerp A Rabbit (The rats)
Catgirl (Female Enkidukai)
Continuing Is Painful (The Death Realm, and Dakkru's Curse)
Emote Animation (Just one- /greet. There are other emote commands but they don't have any animations.)
Enough to Go Around
Everything Fades (More like, everything just vanishes a few seconds after you kill it.)
Fetch Quest
Flat Earth Atheist (Atheist is an option under religion during character creation, even though there are many obvious signs of the gods' existence)
Gender Bender (The god Laanx was originally female)
Guide Dang It (The quest system is notoriously counterintuitive- and what's worse, you can't even get help on the forums, as it's considered spoilers.)
He Knows About Timed Hits (There's a tutorial section when you make your first character on an account, in which NP Cs cheerfully talk to you about game mechanics. It's explicitly stated to be OOC when you start though.)
Hide Your Children (The addition of child avatars is unlikely to ever occur- some players RP as kids anyway.)
Item Crafting (One of the most developed parts of the game)
Its All Upstairs From Here (The Windowless Tower- a subversion, as so far it's completely useless other than for a nice view.)
One Size Fits All
Palette Swap (There are a few enemies that have the same models as other enemies, but different textures)
Pamphlet Shelf averted- There are two libraries in the game, and they have fairly good-sized books, though not nearly as long as real books would be.
Pronoun Trouble (Kran have no gender, so "kra" is used as a replacement pronoun for them, and "gemma" is used in place of "sir" or "madam".)
Purely Aesthetic Gender
Quicksand Box (Many people need help getting through the tutorial, let alone understanding the actual game.)
Relationship Values (The "Faction" points are a variation, in that they show your character's standing with various groups of people or monsters.)
Retcon (Since the game's not finished, there have been several of these)
Capital City (Hydlaa)
Slash Command
Vendor Trash (There's a lot of it.)
We Buy Anything averted- shops only buy certain categories of items, usually the same kinds they sell.
You Can't Get Ye Flask (The quests, again.)