Good game. It needs a limit on how many workers you can have(unless they don't take up any space in the sleeping chambers, in which case that ought to be mentioned in the bestiary-I personally think that there should be a separate worker limit based on how many workshops you have so that there is an incentive to upgrade workshops, and so that there is more depth to the way workers are produced).
It also needs to do a better job of explaining the units, what they do, etcetera(it doesn't have to be too descriptive, but a bit more information in the bestiary would be nice). For example: do the catapults count towards the number of units you can have, or are they free units(the same goes for workers). How do doomers appear? What does "they will come to your dungeon when you have a good food supply" mean-do they come based on how many chicken farms you have? How do demon/warlords get into your army? I would prefer to have all of the main statistics(who does this unit target? what's his health, damage, etc.), but could settle for a general overview that explains everything to the degree needed.
Besides that, a blacksmith's shop or something like that could be a nice addition that could be used to upgrade units. You could also make more in depth fights that have some kind of RTS elements to them, but that would probably be better for a sequel than a small patch to the game.