That's how it works on paper, but the decision is more like this...
Enemy get's stunned more by accident than decision---> glory kill because A: I'm already facing that direction, I move hell fast, and I have to be moving anyhow B: I'll conserve ammo C: It's actually way easier to scoop a glory kill than to line up a last shot on an enemy that is no longer threatening, but will be if I let him recover D: Guaranteed health vs maybe health or maaaaybe ammo E: The invincibility period during the glory kill animation.
I feel like the glory kill is the only way to fly, and when I choose not to do so, the only motivator is that I just felt like mixing it up.
And then the chainsaw is just four chances to restock ammo, or four chances to bus shield guys.
Glory Kills do not provide guaranteed health drops. They're based on how much health you currently have (so they're far more frequent the lower you are) and, as already pointed out by others, this extends to killing enemies normally too with not even Barons of Hell requiring much ammo to truly finish off during a stagger state. Especially on Nightmare this means that they're far from "the only way to fly," so I only end up using them sporadically until I get the runes for shortening the animations and to receive a speed boost when I'm in a pinch. Without them, there's a high likelihood of the enemies catching up to you, or long-range gunfire already heading your way by the time you're out of the invincibility frames grace period.
Even Nightmare feels too difficult IMO. Ultra violence is the perfect ratio of difficulty to fun but I honestly found even the first map a total chore on nightmare. Just frustrating and not fun. Ultra nightmare can do one
Having beaten it earlier, Nightmare difficulty is fine. I do agree that the opening mission is a bit of an initial spike since you lack the wide variety of weapons and various upgrades, but things even out again around the time you pick up the machine gun and the plasma rifle. Perhaps even as soon as you can equip the explosive shells on the starting shotgun if the player has the necessary dexterity for it.
nightmare mode, however, the enemies projectiles practically home in on you like a godamn missle. I get it should be hard, but the spawn points are completely unfair. They spawn behind you, jump on walls so you can't chaimsaw them and their flame balls home in on you like you have a tracking device on you. This needs to be toned down. It feels cheap.
Level 2- during the opening of the gord sacks. The playable area in which to maneuver is way to crowded and small. It's as if you the developers want the player to give up. I just barely beat it in the course of 5 ridiculous hours. Just that one battle. There has to be a way to implement these battle grounds better. But, so it is still challenging without being a cheap asshole. I almost threw my controller out of the window based on how unfair these battles were. However, I love a challenge. The majority of the public won't stick with it if there can't be a happy middle ground for the quick fps. It would be nice not to dance around 1 billion homing fireballs from the same enemies every fucking horde like conclusion. I love the game but fuck! Can we get a different scenario please.
First off, please stop staying that Imp projectiles home in on players on Nightmare. They don't. Furthermore, you
can chainsaw those stuck on a wall although the exaggerated animation doesn't play out.
A.I. patterns, attack behaviour and enemy spawns are more or less identical to lower difficulties. Only the damage values have been significantly tweaked, without it becoming an unfair challenge thankfully. The arenas at the start also give you more than enough legroom to use the layout to your advantage, be it through high ground positioning, ample supplies, numerous exploding barrels and sufficient enough slabs of cover for you to deftly move in and out of harm's way as you're moving towards the next enemy that's out in the open.
Question about the executions/glory kills. I really don't want to do those, and they put me off the game considerably. I find them embarrassing and cringeworthy and I wish they weren't a part of the game.
Is it practical to play this game without using them?
Yes, they're optional. You need to execute bosses with them and you can't outright disable them, but they're not pivotal to the standard gameplay flow.