Thanks for giving it a go! Yes, it needs more visual/audio feedback about things in the world burning and contributing heat.
I definitely want to keep the analogue/intuitive feel! The spell casting system I have planned is built around exploring/using that as much as possible.
In my dev version, you can blow the goblins around with the wind, and later you'll be able to freeze water on the floor to make ice, which'll make things a lot easier to push around and send careening into each other...