The Green Herring
I've attached a demo to this post which shows how to get it. Definitely rather obscure there.
The Darkening - MAP06? I couldn't find out how to get it, either.
As for the topic, I've nothing to add other than that unmarked secrets are a big peeve of mine. In many cases, the author forgot to put the "Secret" flag on the linedef, so I end up finding it by looking at the automap (which I often check when playing a new level,) but other times, I can never find one without throwing on the allmap cheat. In particular, there's one level in 2002: A Doom Odyssey (not saying which one, to avoid spoilers,) where a secret door is placed right next to the exit switch, with no clue towards its existence. What kind of secret placement is that? I mean, even in my first published level (CC3 MAP27, if you're wondering,) there are hints to where the secrets are if you look very carefully. Even worse, as mentioned in this thread, is when these unmarked doors are required to finish the level, more so when they're not secrets to begin with.
Also annoying is when you can't get a secret not because it's too obscure, not because it's too small for you to get into, not because it's otherwise unreachable in some way, but because the secret sector was improperly deleted thanks to an editor bug. By far the most ridiculous example I've encountered was on STAIRS.WAD by Jason Whittington, which has no less than 51 secrets, and yet you can only collect 5 of them, because only 5 of them are actually used on the map. Not even Memento Mori II is immune; on MAP26, only 6 of the 7 secrets can be reached for the exact same reason. I don't think this occurs much anymore, thanks to the rise in the quality of level editors over the years, but it's still rather annoying when I encounter it.
Oh yeah, let's not forget that a sector flat/effect change can wipe out a secret. Definite annoyance there, especially if it occurs in a place where you can never reach the secret in time before it disappears. This is especially inexcusable in a Boom level, where a generalized floor effect can be customized to change only the sector's flat and not its effect. There's actually one error like this on CC3 MAP05 (which at least can be countered by stepping on the pillar before it lowers all the way,) whose mere existence can be chalked up to an oversight on my end as the WAD's compiler (and to being newer to Doom and PWAD editing.) ZDoom corrects this effect, but it's still a problem if you mostly play in PrBoom+ in proper compatibility modes like I do.
This has been downloaded 51 time(s).
- The Green Herring