The last third of Doom II, reimagined by Lutz. And boy, what an imagination he has! Amazing architecture, brilliant lighting and shadows. Huge levels with insane amount of detail. Clever monster usage that doesn't turn into blind slaughter, but still keeps you on the edge due to strategic ammo placement. One of my personal highlights in 2017 when it comes to Doom mapping.
Done on HMP/continuous/saves.
This is an interesting old megawad. Looks and feels different from the usual Doom. That is to say, it's a partial conversion, there're a lot of new textures, new monsters, new weapons, new sounds, and a new character. All of these are combined with a gameplay that is focused not only on killing monsters, but on exploring too. So yeah, Strain is pretty unique, and I liked this change of pace. There are a lot of nice visuals and detailing, not very polished but that's fine.
As something that clearly claims to stay away from the ordinary Doom style, what predominates here are puzzles, lots of puzzles, some are good, some are obscure, and some are the entire level (map 21 ahem...). Also, labyrinths, switch hunts, corridors, lift after lift, and the incidental hordes of monsters to remember you're actually playing something alike Doom. I'm not saying the mapset is boring, no no no, it brings a lot of cool battles, brutal starts, and makes you work your brain, again not in a popular Doom-ish way, to find the exit or grab something important. In many maps, progression is far from intuitive, sometimes you'll cross a linedef and hear something opening or closing, or you'll flip a switch that opens a cabin of monsters that has a wall with different texture that you must open to progress. In other maps, it's quite simple and relies on the typical key hunt. Backtracking is heavily present in this mapset.
About the new monsters, of all of them I liked the Minister of Pain and Dopplegangers the most, mainly because I found them quite funny, specially the mini-cyber which is adorable. Holo-bots are fine, their stealth version can be a pain in the ass. Red demon isn't more interesting than the original, it just consumes more ammo and time. Demon Lords are dangerous, I found that I could exploit their attack from a certain distance, but from close it's best to treat them as a hitscanner, that is to say, covering yourself everytime he shoots. Polydrones are another dangerous enemy, their corpses are damaging and I found myself inevitably stepping on them and aching. They might replace the mastermind but their chaingun is not the super one. Second class imps are creepy. Finally, BFG Troopers are just cheap, specially on map 30, at least they are not that common.
About the new weapons, well the rapid pistol and shotgun are more useful, the double fists are good, the NFG is ok but I didn't like that the maximum was only 100 cells, it runs out so quickly. It also has a safety pin for whatever reason. I didn't understand the BFG replacement, it apparently functions like a slower rocket launcher, and why does it shoot stealth balls? Idk, I barely used it anyway, all I know is that it's powerful.
Secrets, there are a lot of non-secrets in the maps, almost all of them contain a megaarmor (which equals 300 not 200). The midis are good. My favourite maps are 04, 18, 22, and 24. The IoS map is acceptable, but didn't feel like a truly boss map. Map 21 is all puzzles, some without hints, I didn't enjoyed this one too much.
Overall, enjoyable, probably hasn't aged so well. If you're in the mood for anything that I said above, this is going to be your thing. One personal recommendation, there is no pistol start but fists start here, a lot of maps are very very tight on ammo and weird balanced (e.g. punching shotgunners at the start, tons of rockets and no rocket launcher, having to shotgun a lot of demons), so be patient, or try on continuous first... anyway, 6,5/10.