we're looking for games here that were so influential that other developers immediately jumped on the bandwagon for one reason or another. there's a few main criteria here:

1) I prefer imitator works coming from the decade after the release of the original work if possible. this disqualifies things like metroid/igavania or earthbound, which existed as cult classics (to some extent) for quite a while before their style and/or mechanics made a resurgence in the indie scene. we could spend quite a while rattling off indie games that draw inspiration from an older series; that doesn't necessarily mean the original was a strong enough work in its time to cause a fad. compare TLoZ, which in its time caused clones and similar approaches to the action-adventure/action-rpg template to proliferate to other consoles immediately. TLoZ is a particularly strong example bcs its descendents continued to proliferate even to the 32-bit era with Brave Prove and Alundra.
2) there has to be good reason for placing a given game as the particular "hingepoint" in its genre or style. predecessors with influential traits are fine (and I'm trying to annotate them when possible) but if two or more games were highly influential in developing a style, it probably doesn't belong here. a good example of this would be the 80s shmups scene, where there was a lot of competition and bandwagoning for sure, but to the point where successive releases by separate companies actually managed to usurp their forebearers and set new standards. I would almost rather have flash-in-a-pan fad examples on here than something more complex such as that.
3) the imitator works can't come from the same company. for example, if I were to say the yakuza series influenced later games like FotNS: Lost Paradise and Judgment, what I'm really getting at is that RGG studio makes one main style of game more than anything.
4) three examples appreciated, if possible. no worries if not though, I'll try to dig them up myself (and occasionally swap out ones suggested if I can get something closer to the original's release)

---- previous descrip below ----

I don't wanna say as far as "created a subgenre" but basically any game so distinctive that it caused other developers to want to copy the mechanics for their own project. obv no game exists in a vacuum but I'm trying to capture games here that were key turning points for a genre that may have already been under development but were not massively cloned until said game released, so some subgenres that had more organic, slow-paced progressions in popularity probably don't apply. could use some help/debate/discourse since my knowledge has its limits

another good way to put it: anything that has a notable bandwagon of games trying to ride the wave of its popularity. looking specifically for games where its release caused an onslaught of similar games within the next decade