While it is not strictly 64x64 (it has sub-pixels and rotating pixels going on (and some sprites seem to be scaled by a non-integer factor)), it was still fun to play. Losing the game (i.e. getting hit) feels a bit off because the chicken continues to behave as if nothing happened after it, the only instant(-ish) indicator seems to be darkening of the screen.
I like that you can shoot the bullets and that the whole gameplay is controlled with only two buttons. :) I would suggest to making some buttons on the keyboard (and maybe even gamepad) do the same, so the player can pick a preferred input method. :)