A cool stealth game! I liked how you had an indicator for whether the ducks would follow you or not, it was a good touch. I found a bug where if I died in the vents and restarted, the game would think I was still in the vents so I could move anywhere and the floor was green. I think I also got restarted to a previous level rather than the one I was on. In terms of gameplay ideas, I think the vent maze is cool, but it felt a bit distracting in terms of the core gameplay loop. I think if you incorporated more mechanics related to the ducks, it would be really fun and unique. For example, what if you had to make sure the ducks following you didn't get caught by the people that patrol as well? That could add a layer of depth to the gameplay.
But overall still a fun experience, nice job!