Given the proliferation of video games as a form of art and/or entertainment over the past 40+ years, there's no way even more enthusiastic players have tried every major series. I'd be curious to read what influential franchises, or perhaps even genres, people here haven't tried (yet).
For me there's quite a few:
-Mega Man is a good example of a long-running, highly formative franchise that I've just never played. Physical copies tend to be expensive, but that's hardly an excuse in a world of virtual console. I believe I even asked once on this forum which would be good entry points - it just hasn't happened yet.
-Resident Evil is one of the most prolific media franchises, period. There's easily 20-30 distinct instalments and spin-offs, and that's excluding phone and arcade games. Many of them are praised highly, they're on every platform under the Sun, I even own REmake on GameCube. If I have time this October I'm gonna try and see what the hype is all about.
-2D Zelda games Mop It Up made me realise these are another blind spot of mine. Haven't played a single one, nor did I ever try similar series like Neutopia, StarTropics, or Alundra. Although to be honest I'm not going out of my way to rectify this, either. Currently I'm still chipping away at Breath of the Wild and in the future I want to try Majora's Mask, at which point I might be Zelda'd out for a while.
-Dark Souls and similar games are undoubtedly very popular right now. I don't tend to gravitate to very difficult games because I'm generally not very good at games, but I'm open to give this a try if the opportunity presents itself. Maybe on Switch one day?
There's many other series I've never tried, like Kingdom Hearts, Uncharted, Gears of War, Madden NFL and basically the entire battle royale shooter phenomenon. These either don't appeal to me very much, or they mostly exist on platforms I don't have access to. I do want to try a Madden game at some point though, maybe it'd help me understand American football better.
So which major series haven't you played? Would you like to change this? Is it mostly due to constraints on time and money, or a lack of interest too? Are you actively avoiding some series/franchises? Tell us why!