And by some strange coincidence, this week I managed to find the six published copies of the Fabled Lands gamebooks from 1995 by Dave Morris and some other bloke. These are the absolute gold standard of gamebooks (you can have a ship and trade, you have six different abilities/skills, you can store stuff in a townhouse you buy etc...) and now I'm going to be reading them thinking how they could be turned into solo D&D adventures like this one.
Due to a series of bad rolls, my dragonborn paladin died halfway through the adventure.
If you asked me to rate it right now, I'd give it a barely passing grade. My main criticism is that I think the fights are far more complex than they need to be for a solo adventure. Although basic monster tactics are given, dealing with your own actions, plus those of the monsters, plus those of your ally, is quite a lot of things to juggle. In addition, there is a real need for a map and tactical positioning (SPOILER:
Monsters in the first three encounters I played through had the objective of moving the PC and his ally to certain locations on the map.
). In my view, interspersing the complex fights with simpler, one-on-one, round-robin brawls (the staple of most solo adventures) would have improved it considerably.
In addition, there were a few instances where the text was not very clear or which called for a skill check, but did not state what were the consequences for passing or failing (one particularly bad example effectively stated, "Make a [skill] check. Whether the check fails or not, go to X." while X said, "Remember any effect the [skill check] has on the heroes.")
Despite the above, the adventure isn't unplayable. As mentioned, it does get a passing grade. Since it's late where I am, I'll be creating another character and trying again tomorrow.
We should also keep in mind that this is their first Solo adventure (for 4e). I imagine that with an ongoing feedback cycle, they will get better and better so that the mechanical/play issues fall into the background and the story/plot/adventure becomes the focus.