Simple.
One – "I heard about it from a friend."
Two – "It was on my recommended page for Steam/Nintendo E-shop/whatever else you use."
Convince them to get it for you? Harder, but still a bit easy.
"I've seen some reviews, skimmed through a few playthroughs, and (positive things about game; no inappropriate content, the story is good, it's funny, there are a lot of endings)