Boomer and Gen X retired people didn't typically grow up with computers. So, I think part of the challenge is a way to play games that's easy. Probably games on mobile phones are a good approach because the process of finding, installing and launching those games is easy if you're not a "computer person". OTOH, old people's eyes aren't great, and they don't tend to have a lot of dexterity, so while a phone UI might be good, the actual device is maybe too small and fiddly. Games on tablets is probably a much better option.

Steam deck might be ideal, but only if you can bump up the UI font size so that it's more readable if you're older. That would give them access to hundreds of thousands of games. But, the problem is most are probably designed for a PC screen, so they'll have tiny UI elements.

In terms of the games themselves, probably something turn-based would be ideal. I happen to like those kinds of games anyhow. But, as I get older and my reaction speed gets worse, I think I'll play fewer and fewer games that require fast reactions and good aim.

Another consideration would maybe be something social. A lot of older people are still in relationships, and want to be able to do something together. That also means either multiple steam decks so each person can have their own, or maybe couch co-op games.

So, I think it's:

• Turn based strategy, or any other turn-based game -- visual novels might work, trivia quizzes, detective games, just so long as it isn't reaction speed based
• A system that's easy to find, install, and launch games. Even steam for PC is probably intimidating for people who haven't been on PCs for most of their lives.
• Big fonts for people with fading vision.
• Easy controls.
• Maybe couch co-op for couples to play together

Based on that, I can see why Nintendo Wii games were really popular. The system is very easy to use. It runs on the TV so fonts can be nice and huge. A lot of it is couch co-op so couples can play together. They also have a lot of games meant for kids, but those games are also easy for older people to understand and enjoy. They also didn't have sexual / violent themes that old people are sometimes more sensitive about than your typical gamer.

It also shows why Nintendo's follow up consoles didn't work as well. The Wii U had a gamepad. That's more intimidating, and not as easy to use if you have poor vision. Then came the Switch, which was even worse if you have poor vision. Plus the detachable controllers are ideal for kids, but old people now have to fiddle with little almost hidden buttons to detach them. Not good.