I'm a quitter. I come from a long line of quitters. It's amazing I'm here at all.
I can feel bits of my brain falling away like wet cake.
Just to add the official quote to the correct answers above, here is the June 15 post on the Treefrog Games site...
It is with great regret that we have to announce that we no longer have the licence to produce Discworld Ankh-Morpork or The Witches. There is no chance of either licence being renewed, nor is there any possibility for the third game in the series to see the light of day. Since Sir Terry’s passing away earlier this year there has been a change in IP management style. I’m sorry to disappoint those fans looking forward to the next game, just one of those things.