Mineshaft is expert

There is a feature witch blocks a path, you can only activate one each round, it's price is like the tools in workshop

There is also a strange removable object, the large rock walls, Each corner has 3 layers each costs 300 to remove, some has water below

the track is the rails

Red - land

Blue - water

Yellow - path

Green - object above water

Orange - object above land

Edit]:

So I'm participating in a contest

If this were s btd5 map the rocks would just be walls and if the gate thing couldn't happen, well it wouldn't