Alright, I finaly have the time and will to write something about Doom.
Demonastery
For some reason I've never really bothered with single level wads, I guess I felt like they aren't offering enough for me. Well, that might have been the case until I tried playing Demonastery. There's nothing mindblowing about this map, it's just a very enjoyable experience from start to finish. The main feature, of course, is the monastery you go through - it's made of flesh of bones, which you can see right from the begging, but it adds up nicely as you go farther and get to see more obscure stuff. As for difficulty, I say it's fair. The author doesn't try to screw you over with ambushes or ridiculous encounters and gives you plenty of ammo, there aren't that many health items though, so your mistakes will cost you, the hardest part of the map is it's end - arena battle. I highly recommend you to check it out, it's a fine wad and you are likely to finish it in under 20 minutes. Also the soundtrack is pretty cool. I'll repost my screenshots from screenshot thread. Played with Eriguns, I find that they fit the wad really well.
The soundtrack
Doom 404
Frankly, there isn't anything to this wad besides it's gameplay. It's main theme are computers and software (hence the name), the visuals are barebones and in many occasions you wouldn't really understand what the map is supposed to represent if not for their names giving you a clue. Despite featuring a low number of monsters in general, it's a pretty tough megawad, especially in it's later parts. I liked the first half of it better, because the levels seemed more interesting and creative to me, towards the end it turns more into classic "eat revenants and archviles" type of unfun bullshit, it also becomes way more stingy with weapons and ammo. I still finished it, had fun playing maps 1-20, not so much with 20-30. Ran it with Final Doomer, the screenshots won't show you much (I haven't even bothered taking them until the very last levels.), because as I've said the visuals are extremely basic.
Screenshots
Struggle - Antaresian Legacy
I don't have a final stance on this megawad yet, at the moment of writting this post I haven't yet finished it and only played through the 14 maps. The maps in this wad are non linear and I didn't like it at first, the maps 1-5 seemed too confusing and restrictive to me, especially map 5 which features a lot of damaging floors. It didn't help that a lot of rooms and corridors looked the same and I was constantly getting lost, exploraion aspect just didn't grab me. I managed to convince myself to hold on and it was worth it, after 5 map it gets a lot better and levels become more destinct and fun to explore. You get some new guns to play with, they function largely the same as classic weapons, but kill things better: pistol fires in bursts, SSG is more accurate, chaigun (replaced with akimbo pistols) fires faster, rocket launcher does more damage and explosions cover bigger area at the expense of fire rate, plasma gun (replced with high caliber automatic rifle) hits harder; only regular shotgun feels lackluster in comparison to everything else, since the only boost it got is slightly increased firerate, as for BFG I'll let you see it's analogue yourself. To compensate for the buffs to your arsenal you gain less ammo from every pick up and it actually makes things more interesting, because your shotguns can actually run out of ammo. There are some new enemies, I won't comment on them until I finish the wad, but my initial impressions are positive. There are also some tweaks to regular monsters, thumbs up to the author for removing revenant seeking missiles. The difficulty is just right most of the time, although there are a couple of bullshit ambushes, but overall I'm happy with the wad and will definitely continue my playthrough.
Screenshots
Ancient Aliens
This megawad might be the greatest experience I've ever had with Doom. I don't have anything but praises for it, the gameplay, the visuals,
the soundtrack, the new enemies, just everything about it is great. I tried getting into it several times and it only clicked when I went Final Doomer + pistol start. The first episode is definitely the hardest and the most gimmicky one, you would have to maneuver around bigger enemies, while not having access to big enough guns to kill them, there are also plenty of tough battles, where you aren't given much space to move around. But if you manage to overcome it, the wad looses it's grip and maps become easier in general. You will get introduced to new enemy types, like partially invisible plasma shooting soldiers and floating skulls that shoot several revenant missiles at once. I really like those additional monsters, both of them are glass-cannon types and die as soon as you sneeze at them, floating skulls are especially fun, because they explode on death and can hurt other monsters (and player) standing nearby, you can even trigger a chain reaction if they group together, it's such a cool and fun monster, way better than the revenants from the original Doom 2. The levels themselves are very varied, you will go through egypt themed maps, alien ships, outer space, various temples, techbases and more. And majority of them really stand out and don't blend together, the gameplay though is mostly about arena fights, but the pacing and item/monster placement is very good, so it never feels repetitive or boring, I'm telling you this as somebody who doesn't enjoy arena type battles. During my playthrough I grew very accustomed to Skillsaw type of gameplay, where you are given a rocket laucher (and other powerful weapons) very early into the level and have to battle through hordes of demons and aliens. Somebody on the internet described difficulty of Ancient Aliens as "safe hardcore" - you fight hordes of monsters, but you also get a lot of ammo and various powerups, so you are allowed to make a big number of mistakes before monsters can kill you, I agree with it. You don't even have to look for secrets to have basically everything, there was a time when I ate 2 direct hit cyberdemon rockets during one battle and still had spare soul/megaspheres to pick up after that. For majority of people the most "Wow" moment of Ancient Aliens happens when they reach map 24 - Culture Shock, I agree that it's a very pretty and unique looking map, but personaly I was blown away by the map that comes before it - Trinary Temple. You know, I thought that I outgrew times when I could've been seriously impressed by visuals in a video game, but map 23 proved me wrong. I was literally stunned looking at it, I seriously did not expect to see something so cool in Doom, funny that a lot of people consider it to be the weakest map in the wad, while I agree that the gameplay is lacking, but it's just so pretty and atmospheric. I love Ancient Aliens, I really recommend this wad to anyone, except may be those who are just starting to play Doom, I think that the very new players won't fully appreciate it's greatness.
I also wanted to mention some things about vanilla Doom and gameplay mods, but I'm feeling too lazy at the moment, so may be I'll do it later.