In the final release client and server will be merged into one app.
Because the main intent of the game is to be a 4 plyer coop experience. With roguelike mechanics. Meaning - you die and restart.
So there's no need to host a dedicated server unless you are planning to run an MMO like mode on it.
Once the game is released and there are plans for an MMO mod, I will make it possible to run a dedicated server app without the client UI.