I have an X (can’t justify the price to upgrade to the XS, but I’m pretty positive my next iPhone will be a plus/max).
It is hands down the best iPhone I had since the 4S (I had a 6S prior to the X).
So prices aside, go for the XS or the XS Max without doubts, you will be blown away.
I have currently no games that don’t natively support the X, BUT (a big BUT) Race for the Galaxy and Downwell (which is all black so you won’t notice)…YMMV…I tend to complete everything I buy and I delete what I completed but some mainstays…and everything was updated (it’s annoying when it’s not, especially when you try compulsively things with your new precioussssss…RftG not being updated annoys me to no end, I play the game all the time).
That said…I had friends that came from a plus and got a X/Xs and where fine, but some others that felt the X too small…so I would advise you to get the XS MAX.
It’s slightly smaller than your plus, with a bigger screen (and everything else glorious).
The best thing to do is going to an Apple store if you can, and try the XS and the XS Max.
You will probably set for the Max as you are already accustomed to the huge phone.
No matter the huge backlog of unoptimized apps you may have, tons and tons of new games are on the horizon…so it’s almost a non issue imho.