Oh wow, what a cute, awesome, little game! I've just finished the demo and I really wish there was more. It took me about half an hour, I think, but I've taken my time with pulling and pushing all those chairs, plants, lamps, and grandfather clocks around. It was really fun and totally scratched my itch for tinkering with the game's world and surroundings.
The gameplay itself was really pleasant, I'd even go as far as to say it was cozy and wholesome at the same time. It was really nice to navigate around all those small and big rooms, examine, pick up and drop the abundance of objects. And the puzzles were quite clever, reasonable, and satisfying to solve with all the required tropes (clues hidden in plain sight, red herrings).
There are some issues of course, but most of them have already been mentioned (although for me the menu system is a feature, not a bug :D). One thing to mention is that Fn+F10 conflicts with a built-in system shortcut on Mac. And personally, I've struggled sometimes with the isometric view and the controls (i.e. on several occasions I was not sure if the UP arrow would make the hero move north-east or north-west – and I've chosen incorrectly, which resulted in pulling/pushing not the way I expected).
All in all, you've got a really solid foundation for a great game. You've created an amazing little world that sucked me in instantly and left me craving for more. Good job! And I really hope you'll finish this project one day.
Btw. it's funny how often retro detective mystery games follow the same patterns and even have similar objects (I myself am working on a retro detective mystery game and I also have a grandfather clock, parrot, lift...). ;-)