The Witcher Netflix series is certainly off to a promising start. However, attempts to turn video games into movies or TV shows have almost always ended up being flat-out terrible.
Super Mario's Bros, Mortal Kombat, Street Fighter, Resident Evil…(yeah, lots of people like the Resident Evil movies…but they're still just low-budget B movies with bad acting).
Anyway, to answer your question…
A think a Metal Gear Solid miniseries based on the first PlayStation game could be good. Get David Hayter (the voice of Snake) involved. Shit, the guy's only 51 years old. He could even BE Snake. If nothing else the guy really put a lot into the games and I think he'd make for a good writer and consultant.
Fallout could be adapted into a serviceable series as well. I don't even mean 3 or New Vegas. I mean go back to the original story like Netflix did with The Witcher and proceed from there.
I think at some point, though…it will end up being almost redundant to try and adapt games into shows or movies.
Think about games like Red Dead Redemption and The Last of Us. They are so beautifully, masterfully done within the medium they exist that a screen adaptation beyond that would never really be able to stack up against them.
The same goes for The Witcher 2 and 3. They're already vast, intricate stories that you yourself get to really be a part of. Watching something like that on TV would almost be like watching someone else play the game.
Anyway… These are just my thoughts.
As it is, you can watch YouTube videos where games like Metal Gear, Red Dead, and The Witcher are put together like movies with some gameplay and all the cutscenes put together.
We're unlikely to see Witcher games based on the book material Netflix is drawing from currently…so those early tales of Geralt of Rivia were really a bit of an untapped visual market.