Dunnet is a rather old text adventure, which is free, portable, and often comes with Emacs. During the adventure, you will discover a surreal cyberpunk world, as well as new limits of boredom – in case if you like cyberpunk, that is; hard to imagine what the experience would be otherwise. If you think that you are desperate enough and can not be bored more, then you probably have a chance to go through it, or at least to learn more about your feelings.
Another lesson to learn from this game is that interactive versions of things (of fiction, in this case) are not necessarily more fun than non-interactive ones: though you have choices, they are lame, and it is mostly about bruteforcing the options. Of course, there is some sense of achievement when solving a riddle and advancing, yet one can achieve something real with equal effort and more fun in the process.
Despite that, it is one of the best games which I have managed to play in the past couple of years, hence highly recommended to kill your time.