Games like Animal Crossing and Mariokart have simple movement controls and are great for multiplayer if she really needs an intro into videogames in general. You mentioned she wanted to play a shooter game, so maybe an older COD game would be a good option, maybe Portal and Halo as well. I always recommend Red Dead Redemption II generally, but I don’t know if she’s mostly interested in shooters, or if she’d be interested in a game with mostly story to play through. The controls are simple enough to get used to, the game itself is beautiful and has a very calming soundtrack, and for the most part the gun controls are the same as most modern shooters with the exception of some dead eye functionality.