10 Sectors (10SECTOR.WAD)

Way back when in the year 2000, while the rest of us were fighting off Y2K, Doomworld hosted a contest. The goal was to create a Boom map using no more than ten sectors. The idea has more merit than one might think at first, as - to quote DoomWiki - "[a] sector does not have to be a single polygon. For instance, two squares can be separate and non-contiguous, but still be part of the same sector." What this meant for 10 Sectors was a ton of maps that had a bunch of "sectors" that only had ten different combinations of ceiling and floor flat, height, light, tag, and type. A whopping 146 entries were submitted, and the cream of the crop were selected and deposited into this, the 10 Sectors megaWAD.

Alien Vendetta (AV.WAD)

Alien Vendetta started out as a solo project from Norwegian Doomer and speedrunner Anders Johnsen. The original plan was for something closer in scope to Hell Revealed but it slowly drew away as Anders began to invite other authors to the project, among them his close friends, eventually landing in between something more like what are now considered the "classic" Doom II megaWADs of '96-'97 and more obvious slaughter combat a la Hell Revealed. Like any Doom PWAD, it doesn't need a story, but there's one included in the intermission texts. I'm not entirely sure, but it looks like the UAC has been working with Hell. The demons pull a double-cross, of course, eliminating their benefactors, taking over UAC installations, and then mounting an offensive which you naturally must repel and then push back to where it came from.

Congestion 1024 (1024.WAD)

Congestion 1024 is a Doom II megaWAD released in 2005, born from the Exquisite Corpse project, in which a collection of mappers created twelve 1024 x 1024 maps and bound them together as a single, contiguous level. I assume either those involved or those observing found the individual puzzle pieces so intriguing that they made an entire WAD out of similarly sized bits, creating 32 levels of intense action. The rules: the player is bound to a 1024 x 1024 area. They are allowed egress as long as they die upon leaving the 1024 confinement. Monsters, of course, are allowed to be outside the area's bounds and frequently are.