Welp, I'm done with hard mode and likely with DMC1, for some time at least. It wasn't that hard honestly, non boss enemies are mostly easy to deal with, 90% of them can just be nuked with DT attacks + grenade launcher, I've only had troubles with sin scissors, some people say that they are one of the easiest demons in the game, but it seems like it doesn't apply to me. Bosses weren't too bad either, the first time I hit an obstacle was griffon, although DMC wiki says that hard mode doesn't increase health of the bosses, griffon got significantly beefier for some reason, I had to use meteor to take him down, while on normal all I had to do is to DT pistols and fire, I didn't even get a chance to learn his attacks before I played hard difficulty, so it took me about 10 retries to adjust.
Nelo Angelo 3 was bullshit, retarded and just a massive RNG fest:
- has several series of attacks that he throws out at random;
- his attacks are pretty fast and have insane tracking, he can do 180 turns freely, even while using stinger, lol, he also moves forward a lot while attacking, there's no enemy in the game besides him with such insane attack properties (even Dante can't do such things);
- massive fucking damage, he kills you in 3 hits max, which is just absurd considering previous point, there is no enemy in the game that does so much damage with attacks that are that fast, reach so far and track a lot, not even the final boss is capable of this, oh and if he catches you with "high time" you are guaranteed to eat second hit, that's 80% of your life for missing a single attack, nice game Kamiya;
- sometimes he will use single hits which don't leave him open for couter;
- can't rely on parry because some of his attacks can not be parried and sometimes he parries you instead;
- he can act like a retard and just throw fireballs at you, providng a very easy opener for you ... or not, if he doesn't feel like setting you on fire;
- summoned swords, doesn't really need explaining, just more RNG, he can put a sword shield on himself, which does nothing and get down immediately, or throw 5 or more series of random attacks at you, and of course, it's never clear when he decides to do so, he might summon swords 2-5 times per fight. And yes I know that you can knock him down, while he's in the air;
- there is a slim chance that he will hit you with a point blank stinger, it is instant and has no start up at all, but it will cost you about 50% of your life bar;
And you actually kill him pretty fast on hard, DT kick 13 will take something like 1/7 of his life bar, can't imagine how people deal with him on DMD, where bosses have several times more health. It just turns him into "no mistakes allowed" kind of dumb fight, where you have to tear through his massive hp bloat, it took me no less than 12 retries to finaly beat him.
Nightmare was still easy, even despite his increased damage. And Mundus agh, I didn't like fighting him the first time and on hard he became even more annoying, another RNG on top of more RNG, but not as retarded as Nelo Angelo.
But outside of bosses there's nothing in the game that can challenge you really, even getting S ranks is rather easy, you can eat shit all over the place and still get the best score, just don't die. DMC1 only really cares about orbs, time and no items being used (you can still use 1 or 2 and get S rank, but you have to careful with what you do) and timer is pretty generous, only missions with Nightmare have very strict limit for some reason, even though I used every opportunity to attack him, I still ended up with just 40 seconds under the timer, that is fine for hard mode, but how do people beat him in time on DMD, where he has much more health ? I have no idea if you're given more time on the that difficulty though. As for combat, you don't need to be stylish, DMC1 plays more like a beat'em'up, where you can just spam the best attacks and win, you earn more orbs from enemies if have play stylishly, but it doesn't even matter, you will get enough to recieve S rank for mission, even if you just spam 1 attack repeatedly, I feel like "crazy" playstyle is even more discouraged on DMD, because you risk enemies using DT, if you don't kill them fast enough.
As for secret missions, I've done all of them on my normal playthrough, but that was HD collection, while hard mode I've completed on PS2 emulator. I downloaded some save with hard mode and every move unlocked, the guy that made it didn't bother with completing secret missions and I can't blame him, most of those are just annoying to do.
Not sure if I even want to attempt S rank DMD run, may be some time in the future.