Mercenary Kings. I was so looking forward to a possible RPG Metal Slug with weapon customisation etc.
Broken game, terrible controls, constant sound clipping that was never patched, ridiculous gameplay design choices. Just such a disappointment and the only game this year that I'd call 'bad'.
Most disappointing: Dark Souls 2. DSI is my favourite game of all time and this felt like a sequel that had been lead by a develop by numbers book. Bland/forgetful/non-sensical environments, artificial difficulty (which I KNEW they'd do as soon as they started boasting about its difficulty. Notice how DS1, DeS or Bloodborne have never done that), boring boss fights with terrible designs in both gameplay and art. There was just no heart and I think even the development team had lost interest in some environments. Disappointing.