Very cute!! We love duck, we hope duck has a happy life <3
Like others have suggested, highly highly recommend a tutorial. The small tutorial at the beginning was unclear-- I didn't know those flashing things were supposed to be computer mice, I thought they were tables or something from the business building. Maybe some kind of animation clicking the left / right keys? And in terms of tutorials, it took me a few levels to figure out how to know what age / color I need to be to get through a door. For a few levels, I just stood up against the doorway and shot with the left button, then if that didn't work, shot with the right until it opened. I learned eventually though, so maybe no tutorial is needed? But could get both of those problems solved with a simple tutorial though if you ever decide to do more work on this!
Also there's a glitch where the gun just kept shooting and I had to stop it by pressing the same key as the gunshots being fired, but that's a very minor bug.
Overall, amazing sound / music design, very satisfying mechanic and aesthetic, great puzzles. This would definitely make for a great game if you ever decide to return to it, big potential for future puzzles. Right now, it's a good little game if you wanna kill some time with a time gun :)