The game seems to have two difficulty modes,
Too Easy and
Easy. Admittedly, "Easy" is rather challenging, but I was wondering if you could unlock a harder difficulty setting. An old Steam post seems indicate that they were thinking about it:
Easy is indeed harder than Too Easy.
Both names are meant as a joke and only give an indication of their difficulty as related to one another.
As the game is still being balanced, it is hard to say if DotE's Easy difficulty would equate to a Normal or Hard difficulty. It has gone through iterations that would have fit either description.
As it is, Too Easy is a god difficulty to learn the game and unlock things without having to worry too much. Easy is the difficulty that can see you fail due to bad luck or wrong tactics, but that also gives a real sens of accomplishment in the end when beating it.
People have been requesting a third difficulty setting - no idea what that would be called.
but being new to the game, I can't find any info this.