A really fun base for a game. As others have mentioned, the lack of a goal does do a great disservice, but I think it is easily solvable by simple introducing a time limit, smaller levels, and gradually increased complexity and possible interactions from level to level. The windows breaking is a great example of things to introduce, and the first thing that came to mind as a logical next step is pedestrians walking on the sidewalk. Launching garbage at them and knocking them down like bowling pins I think would be very in line with what you've already made here. The models and colors are really pleasing. Great work!