I think the person above you meant “If the copyright clock for the original release keeps getting reset every time an update drops…” and you’re talking about “If each updated version gets its own copyright clock upon release”.
Copyright (and patent) law generally follows the latter in western nations, but there’s nuance because third-party derivative works can easily contain elements which the original IP owners might feel are “derivatives” of newer innovations from subsequent updates, even if the third-party feels they only based their work on the original release.
There’s often a lot of room for reasonable minds to disagree, and it can be difficult to create quality third-party derivatives which avoid any similarities to newer versions of the IP.
Think of creating a modern representation of Mickey Mouse. If you create a new version of Mickey Mouse based on the 1928 version in Steamboat Willy, it is difficult to make something that looks relatively contemporary without creating something that looks arguably derivative of the 1953 work “The Simple Things” or the 1940 work “Fantasia”. You could play it safe by using something that looks like a carbon copy of Steamboat Willy, but if your personal artistic vision involves a more contemporary art style, it is understandably difficult to make it unambiguously not a derivative of more recent depictions that are still under copyright.
For the Starcraft 2 example - in a thought experiment where the 14 year old “Wings of Liberty” version is now public domain but the 11-year old “Heart of the Swarm” expansion pack and current 9-year old “Legacy of the Void” version of StarCraft 2 are both still under copyright. You want to make a new single-player campaign which takes place after LotV and doesn’t retcon any canon events (many of which are still copyrighted). A careful creator would probably understand they couldn’t make any references to Amon being reborn and defeated by Artanis, because that plot is from the still-copyrighted Legacy of the Void. But would you be able to write a storyline that contains any acknowledgements that Zeratul died? (Zeratul died at the hand of his friend, Artanis, due to some of Amon’s mind-control machinations during that same LotV campaign)
I think a creator would have to be careful precisely how their storyline acknowledges Zeratuls death. If its just a few characters generically lamenting the loss of a great/controversial man…probably fine? What if the loss of their friend Zeratul was specified to have occurred “in battle” with no other specifics about the battle? I have no clue. If your storyline includes a tiny quip about Artanis dealing with unspecified guilt/shame over Zeratul’s unspecified death … then that might be technically infringing until LotV falls out of copyright, because some people may feel that it’s specific enough to be definitely derived from the LotV campaign.
Note that all three of these similar examples are where a creator does in fact intend to create a derivation of copyrighted materials to create a sequel campaign to the uncopyrighted work which is still “in-canon” with respect to still-copyrighted works. Its just exploring where is the line of “how much derivation can you morally and/or ethically and/or legally get away with before at least one reasonable person genuinely feels you have elements that are unambiguously derived from still-copyrighted content?”
For “legally” getting away with something you have to consider the costs of successfully defending yourself against lawsuits from notoriously overly-litigious corporations like Disney/Nintendo/Blizzard. Are you so safe that you could get a summary dismissal or is there any reason it could qualify for awards of punitive damages under Anti-SLAPP laws?