No, upgrades in Zelda games should do something fundimentaly new.
I've got nothing against, say, Shield>>Mirror Shield.
As that was a item that did something a bit different.
Even the difference between a lvl1 and a lvl2 sword in Links Awakening gave you a new function (being able to shot).
Likewise, different Tunics had different abilitys. Nothing wrong with that.
But upgrades like "breaks a bit less" dont add to the gameplay, it just means something that takes away from the gameplay takes away from the gameplay a bit less.
And, no, Squidboy, this does not in any way make the game "more complex" just longer &or more tedious.
Zelda should evolve - but by introducing actual new gameplay, not ripping of bits from RPGs. Honestly, its lazy development really - its very easy to make the game longer if you stick the player in a loop of
"defeat enemy, get item, upgrade, this lets you defeat bigger enemys as you have different stats"
Zelda games should not in any way copy that RPG gameplay formular.
Zelda games should be about giving the player a new expirence as often as possible. Items should all do fundimentaly different things, and the developers should try to imagine nice complex puzzles and interesting fighting mechcanics that makes use of those items abilitys.
Using a mirror shield to dazzle an enemy, then the hockshot to rip of his shield, then the sword to finnish the job is infinitely more interesting then. "oh, this enemy takes too many hits I need a better sword" or equivelent.
Same with the Ocarina of Time. Fire would burn up your wooden shield and you'd have to purchase one again.
True, which was also not fun, imho.
But at least that was something you could avoid. If the shield breaks merely by X number of hits, its unavoidable really.
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