This was satisfactory, I suppose. The environment seemed well-imagined and well-described, though perhaps not so thoroughly implemented, and most of the puzzles made sense. A few things were unclued. I did figure out the use of the stone on my own, quite by accident, and that was a bit of an "aha!" moment. I remember reacting with some glee when I realised that the initial area, which I believed to have been cut off, was once again available. The puzzle surrounding the diamond, however, was a little more unfair: I had no reason to go attacking the walls, and I suspect that the diamond would only have been found (without hints) by someone who tried to shoot up the walls of every room. It's an action that is unlikely to generate results, and thus discourages repetition.
There are a number of other oddities, such as the machine gun -- perhaps the goblin had no idea what it was?
All in all, though, there's not much special going on here.
As a breakfast, this would be oatmeal with honey, accompanied by weak coffee.