Lost Pig was my first exposure to interactive fiction in many years, and I continue to be stunned at how immersive, expansive, and unexpected a world the author was able to create with a relatively small map.
I heard it once said that great game design makes you feel like you can do nothing wrong, and Lost Pig is a perfect example of this. The parser was incredibly intuitive, and even though I might not have grasped the solution to a particular puzzle right away, the good-natured humour meant that I was never - not once - frustrated with my lack of progress. There was always something new to examine, and the joy was in searching every room, every object until a hint was revealed. Meanwhile the living, breathing characters seemed to mill about at their own pace, willing to interact but not simply for your entertainment. I wouldn't have been shocked to discover that they had private conversations about me when I wasn't in the room.
There's nothing I don't love about this game!