Tunnels and Trolls has always been notable for the quantity and quality of solo adventures available for the system, and here's a fine innovative example.
Delights include a truly alien environment to explore - the inside of an ant colony - not to mention being a fairly uncommon race yourself: you are a fairy. A captured and battered fairy whose wings have been ripped off, yet. Sitting in a well-lit room at the computer, it's a bit surprising to find out just how claustrophobic the corridors of an ant colony can be but the vivid descriptions coupled with ingenious time-pressure - you've been given a masking scent but it wears off quickly, especially if you get into combat - makes it all quite scary to play through.
Technically, it is laid out clearly in the standard 'paragraph plus options: move to the next paragraph indicated by your option choice' style used by most solo adventures, although the scroll button on your mouse gets a lot of use, no use of integral hyperlinks within the PDF. (I think only one PDF solo gamebook I've read does that, it seems so obvious....).
From the plot point of view, there is quite a lot going on in that ants' nest. As a fairy you are small enough to scamper around without too much difficulty, but there are still some problems to overcome. The twisty tunnels and chambers are not really mappable, and sometimes they collapse. A neat point is the inclusion of 'random encounters' to make everything infinitely variable, as well as set encounters when you get to certain places.
Good luck, you'll need it to get out alive. (I got eaten by an ant-eater...)