Combining the idle clicker genre with tower defence is an extremely cool concept and is executed decently in gameplay, though could definitely use some polish. I also found the exchange rate mechanic to be an interesting addition that develops strategy, as the player must decide if they will exchange the cheese now or risk waiting to get a better exchange rate. That along with forcing the player to decide if funds should be spent on rat defences or improving profit turns a usually stale game from the idle clicker genre into a more strategic and fun game.
The audio selection is good, as the sound effects fit the action they're tied to and the music is calm, which goes well with a clicker game. The visuals are fine and show what they represent, though they could have a more consistent art style with each other.
Still though, this is a solid game 👍