I remember visiting this website once...
It was called Five Nights at Flappy's によって sanic - Flappy Generator Plus
Here's some stuff I remembered seeing:
To create Your Flappy Game, please download and install one of the browsers below:
When You finish playing this game, be sure to make Your own!
This game has been created using Flappy Generator Plus.
Wow, new best score: ! | Can Your friends beat it?