The Lost Episodes of Doom
Three episodes of old school Doom maps. Mostly in a tech/space theme, even the ones that are supposed to be in Hell. Many of the hallmarks of ancient wad design including flashing lights, crushing ceilings and those annoying grids of perpetual platforms (cf. Doom E2M3) Most of the levels were kind of pointless, but there were a few pretty good ones in episode 3. Doom E2M2 tributes, larger maps with more than 100 monsters. This wad could do with having its population boosted a bit, it's very easy.
Apparently this thing has some kind of a story behind it. Technically it's a commercial release; to get the maps you had to buy a book. More about this at the Page of Doom.
On a coincidental but unrelated note, I was reminded of CHRIS.WAD (e1m1cnc.zip) some weeks ago, and thus its remix in that old Spanish megawad, Garrulismo. This time I tried to do the maps from pistol starts. Also tried to get Google to translate the storyline but it didn't do a good job. Something about aliens landing in Madrid but also Osama Bin Laden suddenly turning up and walking around like nothing happened, I don't know.
Anyway I did all of them except 25, 28, 30, 31 and 32. 25 and 28 are just too annoying, the former having too top-heavy a start and the latter being composed of nothing but lost souls and revenants. 30 has a spawner on it so no 100% kills there. 31 is impossible to get 100% kills due to its design; there are two exits obviously but if you choose one it locks you out of getting to the other. I could cheat but it's an annoying, low-ammo map set in some cramped, dark caves, and I have better maps to play. 32 is just boringly repetitive, I think I did it from a pistol start years ago but couldn't be bothered repeating the feat.
The fact that many of the maps have very top-heavy starts, but "follow on" from the previous map (you know, you have a copy of one map's exit at the start of the next, it's an old trick that goes back at least as far as Cleimos 2) suggests the author really intends you to play the whole thing as a mission run, but you get overloaded with ammo and it's too easy that way.