Looks and sounds really nice. And it's cool to see the tower defense genre getting a bit of love!
Unfortunately, the first wave went on far too long. With only one type of tower and a very restricted area to build in, I didn't quite feel that I had enough decisions to keep me really engaged until the end of the wave.
There are also a couple of UX/UI issues. When trying to place a tower over the frozen ground, the cursor showing the "ghost" form of the tower is green, just as it is when trying to place the tower over thawed ground. This caused me a lot of confusion at first. Also, the tooltip suggests that towers produce income, but I never saw this. Instead, the coal burners produce negative income, but the towers don't impact income... I think.