I was going to make a more ambitious, Super Mario Bros.-like game for Flappy Jam, but I scrapped it in favor of simplicity and something I would be comfortable with making really hard.
I present...
(click to go to the jam page)It's basically a playable version of this avatar I made nearly two years ago.

Jump, duck, and duck-jump to postpone your inevitable demise. Go for a high score! Mine is 268.