i think what TES is missing the most are more contextual combat animations which is why characters move so robotic in bethesda games during combat, coz they move as if they are lacking fluidity. not to mention TES cloth dynamics doesn't really look like cloth, compared to other games. (i wanna see cool looking capes and other clothing accessories)
anyways, bethesda really needs to address these issues since even though some of their other features are highly advanced, when it comes to character animations and cloth/hair dynamics, they already look quite outdated.
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as for FPS dodge/rolling mechanics, mirror's edge have shown that dodge rolling while on FPS is doable. but i think there should be a cooldown for dodge rolls so players can't just spam it. (ie : the heavier you are, the longer the cooldown should be for rolls) this would distinguish light armored thief-like characters who are high on agility, and more prone to using dodge rolls for backstab, compared to heavy armored soldiers who would likely rely more on stagger (if they got heavy 2h weapons) or blocking (if they focused more on shields) or parrying/riposte (if they got light weaponry or dual-wielding)
dodge roll spamming in dark souls is bad, mostly coz it looks silly. which is probably why some people hate it so much coz it makes you look like a tumbleweed.
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i also like the idea of being able to change attack animation sets of weapons simply by swapping between attack stances. this would enhance combat so much, and make it more tactical. stuff like being able to hold a weapon with one or both hands, or being able to stow away your shield behind your back, etc.. those are really cool stuff that i think would fit well in TES.
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another combat mechanic i'd like to see in TES are grapples and throws. (mirror's edge is a good example that shows that feature could also be done in FPS and not just third person)
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i would also like to see parkour TES. (assassin's creed is good reference for 3rd person, mirror's edge is good reference for 1st person) both is doable. but i think parkour requires a maximum amount of weight as well as agility requirements.
does it need to be done exactly like AC or ME? nope, not really. but being able to scale some walls and minor obstacles in TES would be good for finding alternate routes and for assassin and thief roleplaying. compared to heavily armored people who might opt for a direct route, etc..
currently, getting around obstacles in TES usually involves clumsy jumps that makes people look like idiots.
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as for magic, i wish they would bring back spell customization. although they need to rebalance it for compatibilities and to avoid the creation of broken exploitative magic.