CHROMA SQUAD!! Super fun and funny game, channeling love for Mighty Morphin Power Rangers. It's the Galaxy Quest for MMPR. Fully aware of all the silly shit in the source material....loves the hell out of it anyway.
You get to build your colorful team of stunt actors turned main actors in their own spinoff show (choosing their names and callsign, action battle cries, the works), and then things take a surprising turn. I'm not a fan of MMPR, or power rangers in general, never was a watcher of it, but holy shit is this game super fun. Each "fight" is an episode of the show that you guys are putting on. The challenges are things to make the show super exciting, and thus drum up fans and hype. Highly recommend it.
If your relative is into sexy anime girls with jiggle physics, AND finds they like Slay the Spire, then NEOVERSE is a good choice. It's unabashedly sexy anime girls in tight clothes, beating shit up. But it's got the same basic setup as StS. I actually really like the fight mechanics, the paladin character especially can be really ridiculous. But, yeah it's some blatant fanservice as well.
Rebuild: Gangs of Deadsville series might be up his ally as well. It's a zombie survival city builder that is turn based. I haven't played much of them, but it might be his cup of tea. And they are usually pretty cheap on steam, all 3 games.
The Shadowrun series is super fun for anyone who is a fan of scifi/cyberpunk, with a touch of magic thrown in there. Lots of variety of character you can play, from magic user to cyberdecker.
Wargroove, which is a spiritual successor of Advance Wars (apparently a favorite from back in the day). It's super fun, somewhat lighthearted JRPG, where one of the champions is literally a dog...in armor...who is just such a majestic doggo, that he can inspire the humanoid troops around him, by the sheer power of his doggoness, to be better soldiers. There is a semi serious story as well but....you know....doggo commander. It's super fun. Very rock/paper/scissors kind of setup for the units and how you can fight each other.
And then the XCOM games, which I enjoy, and found Chimera Squad, that sort of offshoot game they did, to be quite enjoyable.
But yeah, that's my list, discounting the ones I already mentioned. I would definitely recommend a look into the Deckbuilding, as there are a plethora of those games (single player ones, not competitive like Hearthstone), with some really fun systems and rules. Some are basically a D&D campaign, that you build a team, each with their own personal deck of abilities, and you level up, explore dungeons, the works. Gordian Quest is an example of this latter type.
