I'm not placing a vote on this yet - for some reason I can't seem to press enter to play?
edit: OH, it's space bar to start. That's a typo in the game menu

birds designs are cool! Not too much to say about gameplay. Needs a little more time in the oven to get some satisfying punches! Is it possible to make them have physics instead of instantly moving back when they are punched?

Cool Concept .
I think just adding sounds , like bgm , sfx would improve the game a lot .

Nice work !!!