Into game mods and ROM hacks? Then try these on for size (note that they're as ridiculous as ever):
Mega Man 8 Bit Deathmatch: Evil scientist resurrects Killer Robots to enter a tournament, and a few good ones go out to stop him by entering said tournament. They then proceed to blast the nuts and bolts out of each other with a plethora of weapons.
Afraid Of Monsters: Drug addict visits hospital for rehab and is thrown into a pitch-black nightmare world where monsters roam and the source of his addiction are all he has to keep him alive.
The Second Reality Project Reloaded: Turtle king gets help from traitorous robots from another dimension and builds an air fleet within an entirely separate dimension. Said traitorous robots want to turn the world into Stylistic Suck. One of the duo must stop them both.
Brutal Mario: One of the duo is hungry for dinosaur eggs again, but this time ends up in a Mega Crossover.
Portal Prelude: Break the laws of physics repeatedly while being carted around a laboratory by a group of scientists who sound hilariously bad and want to build an insane computer.
Garry's Mod: A mod that lets you... INSTALL OTHER MODS!!!
Touhoumon: The player takes on the role of a child in a world where kids are allowed to leave the house at 10 years of age and traverse the world, capture and force a bunch of familiar girls to fight each other causing them to grow up, and beat up the local crime syndicate. You sick little monkey!
The InTeenimator: Your game, but now with birth control and fertility drugs. And pregnant teenagers.
The InSimenator: Cheating made easy, for those who don't want to learn codes.
Anything on ModTheSims' website: Well, because it just means you have the same game, but everything looks cooler/more realistic. And makes cheating easy.
Blue Planet: Age of Aquarius: Chinese guy with daddy issues travels to a Bad Future, fights space bugs, and becomes an Energy Being to save his father.
Blue Planet: War in Heaven: Mentally unstable lesbian pilot fights in a Hopeless War to prevent a nation of space hippies from being conquered by the space UN and is the spiritual leader of a crew of basket cases to rival Neon Genesis Evangelion.
Terran-Vasudan War Project: A prequel that gets rid of all the aliens and half the features of your fighter.
Silent Threat Reborn: Anal-retentive nerds spend six years creating a Fan Remake of a crappy, rushed expansion pack.
Vassago's Dirge: Classical music is used as the thematic framing for an incomprehensible storyline and Nintendo Hard gameplay.
The Procyon Insurgency: Just when you think a FreeSpace mod could not get any harder, it does.
The 158th Banshee Squadron: Exposition: A prequel where Space NATO fight space Soviets for control of humanity in papier-mache fighters that blow if if looked at cross-eyed.
Super Smash Bros. Brawl Minus: Hackers attempt to balance a fighting game by breaking it.
Project M: Hackers attempt to improve a fighting game by turning into the game that came before it.
Hell Revealed: Doom, only with ten times as many monsters.
Huncraft: Fan sequel to a popular real time strategy game, where everybody dies, and the plot is still not resolved. Notable for being entirely in some weird moonspeak nobody cares about.
They Hunger: A player character without character that wanders through Rockwell has to be rescued three times in his hunt for a disfigured Doctor and a fat police officer.