UAC constructed a bolt-hole on the dark side of the moon which was terraformed for the purpose. It was known as the Waterwheel because of its shape. When you completed the cleanup at Deimos you were warped to the Waterwheel because the infestation had spread even there. You find yourself transported to the centre of the Waterwheel and need to find your way to the exit warp-point cleaning up as you go.
Sadly, the hell spawn has already carved holes into the roof and the upper levels have been flooded. Fortunately, door blocks have prevented the flooding from spreading to the control rooms that make up the wheel(s) and the lower levels where the bugs from hell have constructed their dead-rooms.
I feel like I increasingly come across these Eternal levels where there are wide open spaces that would normally feel desolate and empty, but something about the inclusion of these odd little setpieces makes it feel... oddly touching. It's like he isn't playing by the same rule book as other people. The castle map in this WAD is like being shrunk down and getting to walk around a diorama that someone has built.
Practically a Single player campaign sets in a very dark maze of corridors and ventilation tunnels (reminded me of Aliens TC), conceptually is not a bad map but in reality the broken and cryptic progression made me dislike this, as well as the blocked exit room by a impassible line. Too large for DM too imo. Wasted occasion for something decent.
A little better than vanilla doom 2, final 5 maps are fucking terrible and somehow, they made the icon of sin worse. I prefer the reinterpretations of iwad levels compared to the first DTWID, were i felt the levels were samie and not so different to your typical E1 knock off. Probably i would play it again, maybe not, if you didn't had enough of iwad fix, play this.
Perhaps the best megawad I have played so far. Ancient Aliens is a very distinctive WAD, with its unique tone, custom textures, choice of colors, scenery and meticulous encounter crafting. The overall look of many of its maps is pretty relaxing, (especially as far as Doom is concerned) and that feeling is helped big time by the masterful Stewboy compositions, whose MIDIs often give the journey a mysterious laid-back style or embrace a fun bouncy techno-jazz jive. But don't be lured by the calm looks and sounds, because Skillsaw and his guest mappers know how to turn the heat up and throw you into peculiar and inventive combat scenarios.
Map 1 sets the tone for the action perfectly: after the trippy teleporting sequence, you immediately zoom at full speed past a caged cyberdemon, who will constantly hinder your progress and have you frantically look for the way forward. The following brawl with hell knights, revenants and other foes in tight corners does set a tone for the combat to ensue in the first few maps: resources tend to be initially scarce and berserk punching a few skeletons will help you keep your supplies for fights where ammo truly matters. If that doesn't feel like your cup of tea, do not worry: a fair amount of maps do provide ample supplies for when the heat truly gets turned up. Finally, many big enemies in beginning maps are meant to be telefragged (or, in the case of MAP04, the game will eventually spawn a truckload of explosive barrels to kill archviles with little fuss) so the obvious approach is not always the best one.
The layout of levels often features traps, but at the very least you can't fault the WAD for lack of variety because it's rare that the same trick gets repeated. Encounters are memorable and my favorite of the bunch include a collapsing staircase where you must fight foes quickly under the eye of an archvile, but you must do it fast because the ledges eventually rise up, bringing you closer and closer to him being able to resurrect the fallen monsters. But each time a ledge rises, new monsters can now get to you so you're never safe no matter what! Additionally, the WAD features two new monsters: the plasma marine and the rotating skull cube. Marines make static noises, are cloaked when not attacking and their plasma shots can be hurtful, but they thankfully need to pause before shooting and are very fragile. The skull cubes pack a wallop, firing a barrage of 3 revenant missiles at any time, which can be homing or not. They would be the worst if they didn't have only about 80 health and exploded upon death, hurting everything in their vicinity. This means that when this enemy appears in tight packs, a single rocket can blow away the whole group.
Skillsaw doesn't hog the whole WAD for himself, he offered a few guest spots for other worthy mappers to shine. Joshy from Speed of Doom fame gets two maps, MAP 9 (The Nectar Flow) and MAP28 (Floating Arena). Both are completely different to each other gameplay-wise, but both are fun. The former is a journey through caves of nectar that features the highest monster count in the WAD at the time, but most of them are zombiemen and imps, so happy chaingunning! The latter effort is a slaughterfest that sets the table for the end of your journey. The numbers are high, but the space, ammo and powerups are abundant as well, not making the carnage too mean spirited. Stewboy gets the MAP 31 slot, but this one doesn't work as well; the pacing is too slow and there's a little too emphasis on secret hunting (13 secrets in total!) and the layout even is a little too gray and drab. AD_79's MAP 20 is a strong showing with its tubes full of enemies and the clever archvile hologram trap. Esselfortium's MAP 22 is a scenic ancient castle that is one of the prettiest maps of the set, only upset by MAP24. lupinx-cassman offers a spectacle for the eyes with a sky temple that appears to worship several cultures at once, hence the name. While some of its combat is a little stilted and uncomfortable at times, the looks all make up for it. Tarnsman's MAP 26 is a pretty old stone temple, but the heavy chaingunner usage makes it feel like some weird Plutonia homage. MAP 23 by Pinchy is probably the only guest map I can bring myself to dislike: it's too big, sprawling, confusing, loves to spawn chaingunners that snipe you at great distances and finally, that final fight can go to hell.
As for skillsaw's work, the best part about his works is that he's very consistent quality-wise, I can't bring myself to dislike any of his work in this WAD (MAP 32 might be his only map I didn't really like, it felt a bit by the numbers for a secret secret map). Some of the levels have gimmicks attached to them, like MAP 6's sinkhole, which occurs as you're grabbing a shotgun (?). But you better not think of it too hard, or hordes of shotgunners will come to take you away. MAP 18 shows how dangerous the Illuminati are, with the surprise inclusion of an Icon of Sin (in the form of a giant Illuminati pyramid!) that makes incursions in the main courtyard a tricky affair. MAP 19 is a berserk and pistol level that will get you up to speed with punching enemies, your champion contender here will be an archvile you need to punch down so good luck! My favorite Skillsaw maps of the WAD would be Maps 1, 2, 4, 7, 14, 16, 25 and 29, aka the last regular map of the set. It's 3 big fights, the final of which is punctuated by the shattering reveal of who's behind everything. Then, they get to watch you do the final fight against seemingly unsurmontable hordes in a big, colorful arena.
All in all, Ancient Aliens is a masterpiece. It is surprisingly approachable for being a modern WAD and the difficulty is hard, but often fair. Keep in mind this is still an harder WAD than Plutonia, though. I had a pleasant time on UV with saves and continuous play and if your skills aren't up to the task, lower difficulties will make sure you are not left behind. If you're like me and somehow took this long to finally play this, remedy the problem and play it now. It's one of the all-time greats.