The Second Doctor's era is a crucial one in the development of
Doctor Who as a series. There's the obvious point that the regeneration itself, and the show's re-invention that followed it, are a large part of why it has survived so long. But it's also significant that much of what we now associate with the show originated with the Second, not the First, Doctor. The First Doctor's adventures, as I mentioned in the previous review, were quite different to what we have now, and often at least tried to be fairly sophisticated science fiction, with a focus on alien culture, moral quandaries, and the practicalities of surviving in a hostile past.
While there certainly are some pretty sophisticated stories in the Second Doctor's era (
The Mind Robber particularly springs to mind), there was also a change in focus. This era became about monsters in a way that the first three seasons had never really tried to be - aside, of course, from the Daleks. Other features of the era that have since been commonplace include the 'base under siege' trope, with an isolated outpost menaced by hostile aliens. That's first seen in
The Tenth Planet, the very last Hartnell episode, but it becomes much more common under Troughton, notably describing all but one story in the fifth season.
It's also the first time we have a companion joining for the sheer fun of time travel, and the last of the truly reluctant companions. In this respect, the dynamic of the show is also becoming something we more readily recognise today. It's also, for that matter, the first appearance of the sonic screwdriver. This, incidentally, is first seen in
Fury From the Deep, a story in which it's only used to, of all things, undo some screws! Even in this era, it gets to do more later on...
This gives the second volume in the DWAITAS sourcebook series an advantage that the first volume could never really have. The stories here are more familiar in style, more the sort of thing somebody who'd only ever seen Nu Who (or, indeed, much of the colour era of the classic series) would expect. In particular, there are a host of monsters to throw into our own scenarios, where in the first sourcebook there were only Daleks and a bunch of alien cultures - many of which, like the Drahvins and the Moroks, look essentially human.