Though many reviewers complain about the difficulty of the game -- in which users must repeatedly tap on their screen to make a bird flap its wings and navigate a series of pipe openings -- it has exploded in popularity, causing some to puzzle.
The premise of the game is shockingly simple: "Tap to flap your wings to fly," and "Avoid pipes," the app's description says in iTunes.
"This game is purposely difficult," wrote one reviewer, identified as Gurrrllll. "I think it's a bit silly just how hard it is, but that adds to the charm and desireable-to-download nature of the app. It keep you coming back because you want to prove to yourself you're not an idiot incapable of getting a 16bit bird through a set of gapped Marioesque pipes."
"Graphics are retro as an aesthetic purpose that well compliments the simplicity of the game," the reviewer added.