You’re in darkness—
A flash of light cracks through—
Your eyelids open, but you still see only BLACK.
The back of your skull aches, ringing like a churchbell.
Need to… need to get back…But back where?
You’re lying on your side, but strangely in motion.
If this is a hangover, it’s the worst hangover of your life.
I just finished playing a neat little self-contained text adventure called Trunked. It’s definitely a callback to the days of Infocom games, but the difference here is that this one’s entirely generated using HTML. It’s a quick play, so I’d urge you to give it a shot and see what you make of it. I died three times before reaching (an/the?) ending.
More interesting than the game itself is the toolset that was used to create it, which is called Twine and is available for Windows, OS X, and a command-line version that uses Python.
(And if you want something that’s a slightly more complicated and graphical open source game creation engine, take a look at LÖVE, a toolset for creating games using Lua.)