Any suggestions? Maybe time and number of life as start?
I'm planning rotate the scene and put 2-3 chickens at the same time.
Well, about the bugs, thanks too! I already published another version with them corrected.
Since the game is about capturing the chicken, you could impose a time limit. In this time limit the player must reach a quota of chickens before it expires, for a more frantic experience you see in arcade games.
Additionally, adding some depth to the chicken capturing with a meter that fills up the more chickens you capture. Once this meter is complete you would go into a super mode per say. This super mode can be anything from temporary boost in speed or invincibility to hazards.
Those are two ways of doing it, without doing more art assets for an HTML 5 game.
I'll check it out later for any other bugs. 8)