livinginfantasy

try Darkness 1 & 2 for FPS.

you can always go for older ones since their performances are still great in 2019.

I was about to suggest you an alternatives then I noticed you are bounded with Apple's Ecosystem. Anyways, why an upgrade? if your current iPhone 6S performance is still amazing. It's still a great phone. iPhone XS is your "Want" but not your "Need" (if you know what i mean).

Wish there be lots of mods! "Witcher 3" is still my favorite game but I have always envied "Skyrim" and "GTA V" of having lots of available mods.

PPSSPP for PSP John GBA for Gameboy or else, you can download from many sites.

I do prefer Offline RPG games in mobile. Although, some games that i play are no Genuine mobile games. Here are my few favorites: The Bard's Tale: I do love this game humor, good story, different endings, i can go on...................... GTA San Andreas: Part of my childhood exists with in it. Zombie Tsunami: sometimes when bored Modern Combat 4: Once purchased; free RPG story. reminds me of "Modern Warfare" in mobile version. Eternium: like "Diablo".

Most mobile games offer micro-transactions and parents need to keep their credit card access safe from the kids reach. There are many cases such as https://www.bbc.com/news/technology-48925623 but you are concerned on their future. I say its not only just mobile games but a whole gaming platform has to be limited. Me myself was full-time gamer for a years; didn't slept, studied, ate enough. But i heard wake-up call within me and now I limit my urges to play games more.

I still go for the "Switch" because I can play AAA titled games anywhere i go.