Zombies & building placement added

Its been a while! I have been doing lots of engine work and getting distracted by life stuff, so I didn't get as much time to work on my game as I would've liked, but things are finally starting to pick up again now! There are some new assets and tons of new mechanics.
For example:

• Some visual tweaking to lighting etc
• Placing buildings now gives you "points" depending on nearby buildings (inspired by the game Islanders)
• Zombies are in, with the Dijkstra pathfinding I implemented into the engine
• New train station model and train tracks sprites
  

Later on the building "points" will be changed to "real estate value" and they will be computed in a slightly more complex way, but this is a good start for now.

Zombies
The zombies are treated as rigid bodies, with some of the physics logic stripped out for efficiency, which gives them a hilarious "bounciness", as they slip and slide all over the place (see video). I actually really like this for the zombies, since it makes them seem inhuman and ferocious, but when I implement civilians I will probably go with a non-physically simulated body that can turn on a dime and is entirely moved by script. That should make them act a bit more human and reduce the chances of them splatting into the side of a building at full speed, loony tunes style

Building deletion
I do have one gameplay dilemma that I am a bit stuck on, so if anyone has any ideas then pls share 

Because you get points based on building placement, a key gameplay restriction is that you can't delete buildings once you have placed them.

This has one main problem: its too easy to fuck up

Unlike in Islanders, in my game roads and building access are important. Civilians need to be able to reach your buildings by road, otherwise you won't get a benefit from them. It is fairly easy to accidentally place a building that blocks a crucial road access point, or makes half of the map inaccessible, and then fucks up your entire game. On the one hand you could chalk this up to "user error", but this doesn't feel like a "fun" way to lose. Some alternatives I thought about that wouldn't work:

• If you can delete buildings freely, then you could place a building, get some points, delete the building, and then re-place a building in the same spot to get even more points - space restrictions become meaningless
• If you can delete buildings at the cost of losing some points, its still not great because you don't have to worry about the future too much when placing buildings - "Oh, I can just delete this later if I need to". You can also manipulate the zombie AI by placing a small cheap building to block off a key chokepoint, and then deleting it later once you have safely amassed a bunch of defences right behind it.

NB: Another problem is that you might be able to block the zombies entirely with a giant wall made out of buildings. I already encountered this problem with the 2D version of the game, so I'm gonna use the same solution - check when placing buildings if it will block the path from zombie spawn to the train station, and prevent placement if so.