So recently lots of people are experiencing this. They are not unable to download the game via the Desura client. I have already contacted Desura about this, and I'm waiting for an answer.
Short fix would be to download the Launcher.exe which should be available (this is our own launcher which keeps the game updated)
I'm really sorry for this and I'm working to solve it! Spamming the comment section or rating the game with 1 star wont speed up the process, it will just make all this more painful. So please understand that I'm just one person in this end trying to figure out whats wrong.