But in addition to those, there are a number of maps already included in the pk3. I didn't make any of these, they're all by the masters responsible for the Master Levels in the first place. I've checked the txt files included with every one of them, and they all say I'm totally allowed to distribute them as long as I include said txt files, so they're in the PK3 as well.
Some were meant to be part of the same collection, but rejected, while others are connected by story to maps in Master Levels. Each author's maps are gathered into one episode, with the first three being the ones that form a story, listed in order of when the first .wad of that story was released. These are:
- Inferno, by John "Dr. Sleep" Anderson. A loose retelling of Dante's classic, where you search for your beloved in Hell with the help of space poet Virgil. Levels are sorted in the order listed on the wiki, which can provide you with more details.
- Cabal, by Sverre "Cranium" Kvernmo. The revenge story of a cyberdemon betrayed by his peers and turned into a human. Levels are sorted in the order listed on the wiki.
- Titan, by Jim Flynn. A marine is sent to the moon of Saturn to find "the latest in alien weapon technology". Levels are sorted in the order listed in this review.
I've actually had this lying around on my computer for a while, but I didn't intend to upload it until I'd implemented story screens similar to map00 in Doom 64 Retribution so they could be seen at the very start of an episode and show more than one screen's worth of text. It was only today that I finally got around to looking at the map in question to see how it was done, and it was then I realized that it was too much for me at my current level, so I just went ahead and uploaded what I had.
EDIT: One last thing, if you don't appreciate the ability to carry your inventory from one map to the next, I'm just going to recommend this little addon by Coldiron. It even comes with versions for popular gameplay mods.