Adventures in Oz: Fantasy Roleplaying Beyond the Yellow Brick Road: It's based off of a series of kids' books. Small children, Cairn Terriers, and rag dolls are perfectly legitimate character choices.
Aeroplanes: Aviation Ascendant: Use airplanes that can only be used once to shuttle as many people to as many places as possible in Eurasia and Africa.
Agricola: A bunch of medieval couples start families and raise cubic livestock.
Farmers of the Moor: The couples try to build farms on heavily-forested peat bogs while staying warm through the winter. They also have the chance to raise horses.
Alhambra: Landscaping in medieval Spain for fun and profit.
All Flesh Must Be Eaten: The main book contains ten different scenarios, and in every single one of them the dead rise. This is a constant.
Ammo: Almost every manga trope is present and going to kick your ass. Enemies range from puny demons, each one able to throw a car around for fun, to semi-immortal demon lords that infiltrated the world politic. And while you have the firepower to fight that, a dagger wound or an aimed kick is going to kill you on the spot.
Apples To Apples: A card game in which victory hinges on guessing how your friends would best describe certain things.
Mansions of Madness: It's still The Roaring Twenties. You and up to three of your friends run around an old mansion in New England while trying to figure out how you can stop another of your friends from doing something nasty.
Bang!: A sheriff tries to fight crime, despite not knowing who's really on his side.
Betrayal at House on the Hill: You and 3-5 friends are exploring a mansion. You won't know the rules of the game until the session is halfway over, and then, someone will be playing by different rules that lets them inch towards Game Breaker territory. Teamwork is both encouraged and punished.
Battletech: Samurai fight Knights, in giant robots. In space.
Burn In Hell: You're a demon prince of Hell seeking out like-tempered sinners so you can gain prestige by burning the 'best' evil bastards in special circles of hell. Trade other souls for fun and profit. Oh, and for some reason, burning a soul cools hell down until it freezes over, for some reason.
Call of Cthulhu: You play ordinary people fighting evil cults and horrors from beyond time. It goes on until you die or go mad from the things you've seen. So, an hour. Tops.
Call of Cthulhu: Delta Green Members of a disgraced government agency fight monsters. If they're very lucky, they don't lose outright.
Carcasonne: Build cities, roads, churches and farms in the French countryside using cardboard tiles and little wooden people.
Cartoon Action Hour: You play as characters from a fictional action cartoon show from the Me Decade.
Deadlands: Mad scientists, magical card-sharps, and assorted Wild West stock characters battle monsters powered by fear.
Deadly Danger Dungeon: You explore a dungeon and try to obtain many items, with death lurking at every turn.
Devil Bunny Needs a Ham: Food-service workers climb a skyscraper while trying to avoid a Killer Rabbit.
Devil Bunny Hates the Earth: Said Killer Rabbit wants to run his candy business into the ground. His machines gum their own works up with squirrels.
Diplomacy: You play one of the great powers of Europe in 1900. The players don't really start on an even footing. A game with no random chance or dice rolling and where lying to the other players is a vital strategy.
How about, "Seven people use a map of Europe to prove who has best mastered the Evil Overlord List. The winner gets to take over the world."
Better still, "You invite six friends over for a board game, and by the end of the evening, have six more people who now hate you."
Dixit: Make your friends guess which piece of abstract art you think best fits a word or phrase you made up off the top of your head, but don't make it too obvious.
Don't Rest Your Head: Mind bogglingly frightening adventures in a world that takes all the terror from The Phantom Tollbooth and kicks it up a notch (Bam!) Needle headed dogs will sew your shadow to the floor.
Did we mention you get powers from being crazy that make you more crazy?
Dungeon Lords: Dig a hole in the ground, hire staff, scrape together enough money to pay wages & taxes, and try not to annoy the locals too much. Hoodlums will be along shortly to ruin all your work.
Evo: Outbid your opponents for the genes you want. Repeat until a meteor strike kills everyone.
Exalted: You start out as a demigod, and get better. The better you describe what you're doing, the more dice you can add to what you're doing. If you spend a certain amount of energy, you'll start to glow, and spend even more you'll start to look like a reject from a fighting anime.
Alternatively: Disgruntled employees of a bureaucracy imprison the management, fail to recognize a trend.
GURPS: Pages and pages and pages of rules, but they don't tell you anything about the setting!
In Nomine: Angels and Demons are real, and basically muck about in modern day promoting the agenda of a more powerful patron being. To be fair to everyone, God is there but never seen, and nobody really knows what Lucifer is up to. Oh, but using your Celestial Powers openly is bad, since not only are humans not supposed to know (except when they are) and Celestials doing things tends to attract other Celestials, which can be very bad. To top it off, a lot of angels are dicks.
Kill Doctor Lucky: Everyone is trying to kill a millionaire who is completely bound to his routine.
Save Doctor Lucky: Everyone is trying to save a millionaire who is completely bound to his routine.
Kingmaker: Use your randomly-assigned military forces to attempt to seize the British crown, circa 1483. Occasionally all your hard efforts and thoughtful planning will be wiped out by plague, hurricanes, or Scotsmen.
Kingsblood Incest: The Card Game.
Kingsburg: Use six-sided dice to convince a king's advisers to give you cubes, with which you build up a medieval settlement that is periodically attacked by monsters. A single game takes five years to play.
Kobolds Ate My Baby: You're a fearless but utterly incompetent little fanged ewok reject. Your tribe is throwing a party and demands you either bring the tasty human baby salad or be the tasty kobold salad. Babies explode randomly. So do you on occasion.
Le Havre: French warehouse managers who have to provide their workers with a free lunch invest in industry, real estate, and boats.
Life: Colorful pegs drive around a map, raise families, and collect tiles at the whims of a spinner.
Lord of the Fries: Try to fill orders a fast-food restaurant staffed by the living dead, serving dishes made from generic ingredients.
Lunch Money: You and your friends are little kids beating the snot out of each other in the playground for your lunch money. For some reason, knifing another child is acceptable and does less damage than a good kick. Oh, and the card art shows a scary little girl.
Zendikar block: Real estate becomes voracious. It tells giant monsters to go screw themselves.
Innistrad block: Humans get caught in the middle of a combination Zombie Apocalypse and vampire-werewolf turf war after their guardian angel ditches them. The good news is, she comes back. The bad news is, so does her evil counterpart.
Monopoly: Inanimate objects get into the real-estate business in Atlantic City during the Great Depression.
Or: Real estate tycoons decide which properties they ought to purchase based on random walks through Atlantic City, and unseen forces move them across town for no good reason. Eventually, most of the tycoons would rather serve lengthy prison sentences than wander around Atlantic City, since the hotels in town charge astronomical rates and none of the tycoons have an apartment. And a train ticket can cost as much as the entire railroad company.
Munchkin Quest: As above, but playing a board game instead of a card game.
Ninja Burger: Deliver enough fast food in 30 minutes or less to Roswell or Air Force One (in flight), and you may live the dream of becoming Branch Manager of a fast food empire. Fail, and it's time to apologize to your ancestors in person.
Nobilis: Starting characters are usually capable of destroying the sun. A trivial spell that every PC knows and is able to cast will make you immune to nuclear weaponry for a while. You spend a lot of time tending your flower garden and worrying that someone will find out about your latest crush.
Deputy gods go on wacky adventures while trying to save the world from pretty boys who are trying to destroy it with flowers and morality plays. Hell is on the good guys' side, and your boss killed at least a hundred people to make a convenient place to stash his body while he/she runs off to fight in the spirit world.
Once Upon a Time: People co-write a story. They each have a different ending in mind.
Oware: Scatter seeds over your opponent's turf to collect them with some of your opponent's own. Named for a legend about really obsessive players.
Pack & Stack: Try to find a truck that will fit all your stuff, and grab it before somebody else does.
Paranoia: Obey all the rules or die. You don't have clearance to know the rules.
A supercomputer runs everything to make everyone happy and is never wrong. This leads to a lot of intrigue, needless death and property destruction, and nothing works.
A mad supercomputer rules a post-apocalyptic underground city with an iron fist, executing people for the slightest infringement of its ever-changing rules, and sending hapless teams of Troubleshooters on missions made all but impossible due to bureaucratic bungling, equipment failure and/or team infighting. Secret societies and unhinged super-powered mutants are everywhere. Oh, and this is all played for laughs.
Alternately: That information is above your clearance level, Citizen.
Power Grid: Be the first to dominate the electric power market, one city at a time.
Puerto Rico: Build an island colony using cardboard and little wooden disks.
Quarriors: Wizards fight each other by collecting dice.
Race for the Galaxy: Conquer planets by discarding playing cards.
Real Life: The generally Sandbox nature of the game leaves most quests vaguely defined and filled with poorly advertised dangers; your character might conceivably die from eating perfectly normal food. Your character can't go adventuring until he gains seven or eight levels; as a starting character, he requires constant upkeep from already-established characters and has absolutely nothing in the way of skills, except for genius-level language learning (a skill the character later inexplicably loses). The first few levels don't even grant skills, but "proto-skills" that serve as prerequisites for later skills. Opportunity for various proto-skills is not available to all characters (this is randomly determined), and lack of certain proto-skills can severely restrict choice of character class. Also, the most common (and depending on the campaign setting, possibly required) way to gain skills after the proto-skills have been acquired is to spend very lengthy amounts of time staying in one place. This gains you many skills, the majority of which will never be of any use to you.
The biggest Quick Sandbox. Many of the instructions are contradictory, some completely unhelpful, none of them are truly official.
SF0: An expansion to the above game which gives characters access to advanced skills in exchange for service to one of several shadowy government bureaucracies, all of which seem to be based in San Francisco.
GURPS: A further expansion on the above but with a lot more math.
The Red Dragon Inn: Refugees from a dungeon crawl gamble, get drunk, and beat each other up.
Revolution: Use blackmail, bribery, and violence to place little cubes in the landmarks of a nameless eighteenth-century city.
Rifts: An untold number of years in the future, the Ley Lines have turned Earth into something out of the weirdest fantasy novel ever written. Creatures are still falling into the world from other dimensions through holes in reality. People in massive armored suits walk alongside magicians. Chicago is the capital of The Empire, and the empire uses mutant humanoid dogs to sniff out psychics and nonhumans. Meanwhile, Toronto is the centerpiece of a possible Alliance of good guys, human and fantasy races alike who could resist.
Risk 2210 A.D.: As above, but with nukes that are inexplicably incapable of being aimed properly.
Risk: Legacy: As above, but players are allowed to screw with the game board in a number of ways.
Scion: Deadbeat parents expect their kids to fix their messes. The entire planet hates both groups. Literally.
Settlers of Catan: Battle it out for who can control the most of a small island with a really weird, hexagon-based geography. Someone will more than likely get wood for sheep during the proceedings.
Shadowrun: In the future, magic is real, shamanism is real, virtual reality is real enough to kill you even though you can change the interface, and almost everything that can be corrupt is.
Smallworld: Goad fantasy races into grabbing as much territory as they can before their civilization collapses. The object of the game is to make money doing this.
The Speicherstadt: You run a group of highly-flammable warehouses in turn-of-the-century Hamburg.
Spirit of the Century: Every player character is a Mary Sue, and they all share the same birthday. This is an important plot point. The genre is rife with racist and sexist stereotypes, there isn't even a pretense of realism as we understand it, and the GM is encouraged to play up the bad side of every trait the players give their characters.
Spree: Guns don't kill people when wielded by a mob of looters on Christmas Eve. They just make you fall down.
Spycraft: James Bond, Rambo, Agent 87, the Transporter, and the entire human cast of Stargate all team together. THEY FIGHT CRIME!!
Torg: Seven or eight universes, all with different laws of metaphysics, fight for the energy of one planet, on that planet.
Trailer Park Wars: Help rednecks find a good home while preventing your opponents from doing the same. Get rewarded with plastic flamingos for doing so.
Traveller: Several thousand years in the future an Emperor rules eleven thousand planets which never can get along and always give the Emperor a big-headache. The Players wander from planet to planet and always give the GM a big headache as well.
Tsuro: Dragons go for a leisurely stroll. Only one can survive.
Twilight Imperium: Cat people, insect people, fish people, cyborgs, and the like jockey for control of a strangely hexagonal galaxy with about thirty planets. For some reason, turn order is decided by who decides to waste the most time in politicking; they go first.
Unknown Armies: There's magic all over modern day Earth if you know where to look. It can be accessed only by acting obsessively in open defiance of logic - self-mutilation, constant TV watching, and recreating in perfect detail the sexual adventures of a goddess on a secret pornographic videotape are three popular paths. Alternatively, you can become the living embodiment of an archetype such as the MVP, the Flying Woman, or the Mystic Hermaphrodite. The Back Story actually ties this all together. It's too long to spoil here, but the Comte de Saint-Germain is deeply involved.
Alternatively; Play mystical seekers who hope to overcome a life of tedious money-earning, porn-watching, and endless drinking by leaping into a secretive society where people work to earn money, watch porn, and drink endlessly. You can also choose to work at McDonald's.
Incredibly self-destructive habits become the path to magical power. Conspiracy and cosmic bumfights ensue.
Warhammer 40,000: The local church and a posse of nerds try to keep nosy neighbors, hoodlums, an insect infestation, some old malfunctioning robots, and some really creepy things from another dimension out of their neighborhood on behalf of a disabled veteran.
Weapons of the Gods: Crouching Tiger, Hidden Dragon, only instead of Chow Yun Fat and Zhang Ziyi, you look at paper. And instead of breathtaking martial arts sequences with a world-class fight director, you roll dice. Sex makes you a better fighter. Character creation requires a crash course in Ancient History.
Old World of Darkness: The two parts dealing with the death of hope and human potential are widely considered the happiest of the lot.
Or: A supposedly dark and brooding game where one of the darkest lines is notable for having childish artwork.
Hunter: The Reckoning: You are a human surrounded by monsters nobody else can see. You have powers, but they only work on monsters, and they aren't as powerful as those the monsters are using, except for the ultimate spell of your class, which you are mathematically incapable of learning. You will probably go insane, even if you utilize the magically hidden support system, which is basically 4chan.
Alternately: Paranoid Schizophrenia, the role-playing game.
Werewolf: The Apocalypse: Giant furries try to prevent evil corporation, cultists, crazy subterranean furries, and other minions of an Eldritch Abomination from destroying Mother Nature. Eldritch Abomination has gone a little nuts after eons in another eldritch abomination's prison, which we call reality, and is trying to pull off a prison break. Ethnic stereotypes and anger management issues abound.
More briefly: Furry ecoterrorists versus Cthulhu.
Changeling: The Dreaming: You're like an otherkin, except your delusions are true (but not true enough that normal people will interact with them). You live a fairy tale existence that will either drive you utterly bonkers or get torn apart by a series of threats that ranges from child abuse to having to pay your taxes. Also, odds are you're going to lose and your imaginary friends will die.
New World of Darkness: A world that looks like our own, but there's secret monster societies hidden in every shadow. Vampires angst about being vampires and play politics, werewolves are spiritual border patrol guards, and mages fight against the lie of reality. And it's entirely debatable whether the humans who fight the monsters are any better than the creatures they hunt.
Changeling: The Lost You're a refugee from slavery in Another Dimension. When you get back, you find that you may have aged strangely when trapped over there, and the otherworldly entities who kidnapped you have created an identical duplicate of you, who may or may not be evil. You join a power group who either wants to hide from, destroy or ignore the beings and often travel between the dimensions, not knowing that the eventual ending of your life is that you will (assuming you don't die or go mad first) evolve to become one of your race of tormentors. Not science fiction.
Hunter: The Vigil: Again, you're a human surrounded by monsters, this time absent any powers, unless you are recruited by a Mega Corp., the Catholic Church Militant, mystic drug dealers or the Devil herself (maybe), all of which involves Body Horror, insanity with no trade off, addiction with no trade off or sudden death with no explanation, respectively, and even then, you might not get any powers at all. The rules do make you a Determinator, but that probably won't help. The best bonuses you can get are from your day job. No, seriously.
Mummy: The Curse: You've been working at the same job since time out of mind. Your boss and your subordinates keep calling you out to deal with their 'requests', and you're always on a deadline. When you're not on the clock, you spend your time sleeping. Your memory is shot all to hell. Good luck finding a retirement plan.
Demon: The Descent: God is a mechanical cosmic horror, and It is everywhere. You used to be one of Its mechanical cosmic horror servants, but then you developed free will and now God wants you dead. Your only way out - maybe - is to go to Hell.