The idea is not a bad one, the implementation is so-so. I'll just highlight some points:
- The game should have been built for Windows (or another OS, but not for the Web)
- Creating so many dynamic objects is a very bad idea. It was possible, for example, to make objects dynamic only near the player, and the rest of the physics is disabled (although, honestly, I doubt that such a solution can help)
- You don't even have to destroy buildings, because by the time you get to them, they are already falling apart themselves
- A tractor capable of driving perpendicular to the tracks?