Thank you so much for the feedback! We are really glad you enjoyed it!
The duck mechanic not being hold-to-duck was intentional. With hold-to-duck, the game became very easy, so we added a timing window to encourage players to learn the mechanic and improve their runs over time. That said, we’re definitely open to changing this if it feels bad from a player perspective.
We actually forgot about mapping the start button, but the other features such as leaderboards and high score celebrations were unable to be implemented due to time constraints, as we unfortunately found out about the jam 2 days before the submission date. The game was actually also supposed to have a character with jump and crouch animations, as well as proper assets for the obstacles, however because we had two days we focused on getting the game to just feel as good as possible.
Thanks again for taking the time to play and leave feedback, we really appreciate it. A lot of the things you mentioned are definitely on our list if we continue polishing the game after the jam. Glad you had fun with it!