I got an email from Jacek Dobrzyniecki, who flagged up some mistakes I'd made in the book. Tad embarrassing but my ego can swallow that in favour of the book being, like, proper correct, and all that. I'm pasting in from his email below - and a big thanks for that! (also the article he links to at the end is really worth reading if you are into DOOM at all...)
to me Hello
I've greatly enjoyed reading "Doom: Scarydarkfast" (what is the official capitalization of the title, anyways?) and I've got a couple of remarks to make.
I'm really glad for the level-by-level analyses, though they contain a couple of tiny errors and inaccuracies. For instance, the description of E1M9 mentions a trap which makes the room fill "with Pinkys, Imps, and Troopers", while in reality the trap includes Pinkies, Imps and *Spectres*. The guide to E1M5 mentions a secret involving "two pillars, which drop monsters into the room and then raise once (but just the once, meaning a choice must be made)", but actually these pillars can be retriggered any number of times.
Writing about "the final run through large open corridors packed with Cacodemons" in E2M5 (Command Center) seems to be hyperbole, as even on the highest difficulty level this area contains two Cacodemons, at most.
The description of E2M6 (Halls of the Damned) mentions a room with "four switches, each behind pumping pistons", but in reality the room contains nothing but four regular monster closets with Lost Souls and a Cacodemon.
The description of E2M7 (Spawning Vats) likewise makes a mistake when it refers to the "last room, with its switches and rising walkway over a fiery bloodbath"--there is a fiery, red-bricked alcove in the last room that opens up to reveal a Cacodemon, but the room itself has a pool of nukage, not blood. (Incidentally, nowhere in the book is the word "nukage" explained--it is, as far as I know, a neologism coined by the Doom community, and not immediately comprehensible to non-Doomers.)
This may also be nit-picking (as if the rest of this e-mail isn't!), but, in E3M3 (Pandemonium), the sentence "a bridge leads over the only blue water in the entire game" isn't correct; not only there are other places in "Inferno" where the blue water texture is used (including -- in E3M3 itself -- on the ceiling!), but E3M6 (Mt. Erebus) includes a very large and prominent, blue watery lake.
The opening area of E2M7 (Limbo), described as "a large lake of lava", is actually a lake of blood--not that important, but it's a vital visual setpiece of the level.
Some more things I've noticed. You refer to the URL http://toastytech.com/DOOMa/index.html as defunct. But in fact the page is still there--except at http://toastytech.com/dooma/index.html (damn picky capitalization!)
Chapter 14 refers to "eleven discrete ports" of the game described in Ledmeister’s FAQ, forgetting about the twelfth, Tapwave Zodiac port (it's an obscure console, but a port all the same.)
The Penumbra series of games seems to be absent from the Index.
Regardless, thank you for writing the excellent, absorbing, well-written book--it's refreshing to see an increasing number of video game related literature for the common man. It's a pity the book seems to have mostly gone under the radar of the Doom community. Doom, with the sheer number of innovations it has introduced and the new era it has heralded in video gaming, is one of the few games that really benefits from a very close, detailed look at every single element of its design--after all, many of the game's ingredients are the first of their kind in game design in general.
On a lighter note, have you read this interesting article? http://realm667.com/index.php/tutorials-mainmenu-138/1329-medium-layout-a-structure-in-doom - it demonstrates how doors, lifts, and teleporters are used throughout the game, and how they affect the atmosphere, visual design and gameplay.
Thanks again, best regards, and Merry Christmas