Oh, we really wanted to implement more, but time constraints and all. I'm glad you enjoyed though!
Theoretically, the ducks would have a faster spawn rate as the game progresses, but I'd say it needs some tweaks. There's a couple of other things we have in mind to make it a bit tougher, though. :)
Thank you so much for taking the time to play our game and leaving such thoughtful feedback, we really appreciate it!
(Also, that's a crazy highscore! You're #1 on the leaderboards now!)