There’s really no better sign of a game becoming a cultural phenomenon than by spotting an influx of indie-developed games pop up (specifically on GameJolt) that either spoof or rip off the game completely. Naturally, with the humongous popularity that Flappy Bird briefly experienced (and its recent demise), the indie scene has been quick to make its mark in one way or another.
Here’s nine of the most recent examples, all of which can be played for free:
SUPER IRONIC CANDY THEMED SCROLLING GAME (by SuperAwesomeGames): Spoofing both Flappy Bird and the recent drama concerning Candy Crush developers King trademarking the term ‘candy’, this game has you avoiding candy canes and collecting candy pieces in an attempt to beat your high score. Standard Flappy Bird gameplay, basically.
Simple Bird (by Nitro987): Created in roughly half-an-hour to prove its source’s simplicity, Simple Bird plays exactly like Flappy Bird, although admittedly slightly easier.
Shitty Bird (by Sloth Soft Games): Well, spoofs often do take a turn for the immature. Shitty Bird plays similarly to Flappy Bird, albeit has you dodging falling poo instead; not bird poo, but what looks to be human poo because that’s the best kind of poo.
Kill Them Flappy Birds (by FileCorruptedGames): Mocking how Flappy Bird was fast becoming ‘the new Angry Birds’ in terms of addictiveness for the general public, you play as an Angry Bird attempting to zap down the passing flock of Flappy Birds before they pass through the pipes.
Cat Flap (by DavidGeorgiou): The game’s description states ‘Cat Flap puts a whole new perspective on indie gaming, one of a kind wow fun’, but in reality it’s more of a generic Flappy Bird clone with lowered difficulty and not all that ‘wow fun’.
First-Person Flappy Bird (by Christopher Hall): Perhaps the most interesting alternative to Flappy Bird on the list, this game manages to differentiate itself by adding in an interesting first-person element to the typical gameplay, somehow making it perhaps even slightly more difficult than the original game.
Flappy Bird Obvious Rip-Off (by Williamos98): Somehow an even more minimalistic, simplistic game than even the original Flappy Bird, this game doesn’t beat around the bush and acknowledges its roots even from its title.
Floppy Fish (by Matt Brinza): Plays almost identically to Flappy Bird, although with literal sprite rip-offs of Mario’s green pipes this time around.
Flappy Uncle (by Dr. Nu): Another generic Flappy Bird clone where you play as a creepy beardy bat thing whom is apparently also an uncle. Marvelous.
Coin Arcade 
FlappyBird.com?