flappy bird is a simple game, 1000 lines sounds like a normal amount(assuming there is a graphics scaffold, which in this case appears to be SDL), and it would indicate that it's not compressed code-golf style
Indeed. The linked project is quite verbose in fact. Just checked my old ncurses clone in Python and it had 280 lines. JS clone based on Pixi had less than 200. It wouldn't be much more if translated directly to C.