You can't get on RE6 and not mention 4&5 as well.
Oh, I do, but they're not the extreme that 6 is. 6 is borderline beat 'em up.
But it totally changes information conveyed by the environment and how you react to it.
Not in any way that will prevent it from being a Resident Evil game, Neff...
Anything that was done in third person fixed or over the shoulder can be done in first person.
Hearing enemies before seeing them? Put them behind a door, around a blind corner, on the floor above, on the other side of a wall, behind you, etc, etc.
Another facet to fixed cameras was keeping fights difficult through limiting player capability - but that has always been a terrible design philosophy. In RE's case it was shifting camera angles within a single room. As a result the enemies were largely slow and their appearance on screen was beyond telegraphed. In RE4's case it was the inability to strafe or move whilst aiming. So they compensated by having enemies run up, swipe, and then step back to ALLOW you to recover - when the simple truth is that full player mobility plus deadly enemy attack patterns and AI is a more straightforward system that doesn't have to make compromises on gameplay or hamper the player.
Old Resident Evils were not to designed to *play* from a fixed perspective because it was first and foremost
optimal for combat. Not at all.
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How about items? Loose items that need to be picked up from some stray corner of the room? Let's be honest, they usually flashed and were unmissable and later on the maps would start telling you that you hadn't found everything in the room...
The RE7 demo already started pointing to more complex exploration than most classic RE areas. 'By the way you might want to pick up this flashing ***key***'. The old games even had quick cut scenes to show an item falling, post-boss fight or event! A fixed camera might frame a crank handle in the corner in a very artistic way but their placement was never a gameplay highlight. The satisfaction came from wondering what you had to do with said item once you had space to pick it up. That has nothing to do with the perspective. So, the way that information is gleamed from a fixed angle - is that really preferable? Or is it not better to hunt for things directly, in free perspective, and with no hinting?
Shooting? Aiming for a zombie's head to take it out with as little ammo as possible is the same thing either way - it's just a lot more practical with free aim. It sure was always the objective. Fixed perspective certainly doesn't offer the better gameplay solution there.
If there's a shotgun on a rack on a wall, and lifting it off sets a trap, it doesn't matter how you view it. It's the exact same boobytrapped location design, regardless.
Burning a zombie to prevent reanimation - a sub mechanic tackling enemy development - perspective doesn't change anything about the mechanic or the resources involved.
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Literally the only thing that is going to suck in first person is the old 'push the statue' puzzle - and they were terrible anyway and shouldn't come back.
For all the imagined nuance, the games can be broken down into very simple examples of mechanical catharsis that can be achieved in any chosen perspective:
Pick up ammo - endorphins.
Shoot zombies and manage to save ammo - endorphins.
Pick up key for that door you passed - endorphins.
Realise you have access to new areas and are progressing - endorphins.
Pick up new, more powerful weapon - endorphins...
...and so on...
Pace it all just right so that you're steadily progressing but equally mystified. Set it in a locked-in location that forces you to progress past monstrous enemies that are primarily vanquished via combat, and not evaded.
That's Resident Evil.
The only complaints about the first person perspective I will ever sympathise with are from those that suffer motion sickness. That is absolutely understandable. Anything else I've heard tends to lack serious consideration. They're kneejerk reactions that the game isn't exactly like it was 20 years ago, despite potential improvements.
It's this mentality that lead us to COD4 Remastered and not COD4 Remake... an absolute waste.
What if playing first person allows them to, for example... expand upon the old environmental attacks to a more intelligent standard, that couldn't be done in fixed camera?
I mean, the one resounding thing people are saying (second to complaining about first person) is 'I want combat. I want to see gunplay'... and yet... what, they want fixed camera? Auto aim... ?
'There'd better be a focus on gun combat that I have little control over, Capcom!
...
You better limit my vision with awkward framing instead of making the enemies a challenge!'
It's entirely backwards.