Awesome setup! The beginning reminded me a bit of berry bury berry so I was not expecting a full on horror game. I will say, I was also confused at first. I just kept starting and watering the flowers over and over. I had to come back to the comments to check what to do until I read how to start the actual game. It is a cool twist though. I like it!
Maybe after 1 or two plays, you should remove the play button from the main menu and only the quit button remains. Then the player will be forced to start the game.