I think the reason it's acceptable when they when they are that young is because in Japan the age of consent is 13 if I remember correctly. And youthfulness (With it's intricacies) are much valued there. Sure, I would love to retry some of them again. =)
PG-13 hmmm... well Akiba's trip. Luckily I play on the Vita. Lol If I can mention a mature game, the Virtual Cameraman series on the 3DO. Fun and challenging.
I enjoy Devils Third. I don't regret getting the physical copy. I enjoyed it and the online. The game is dumb yes but I liked to look at it in the sense of Dolph Lundgrens stunt double direct to video 1994 action film the game. B movie tier cheese in a so bad it's good kind of way.
Mine? Well....Teen Titans for PS2,and the show itself in general. Seeing Raven always made me feel weird back then. Coming back to the game and the show now makes me feel nostalgic now,and the game actually looks much cooler than I remember it.
When I was 14 I went into GameStop and asked my mom to buy me spongebob video game for game boy advanced sp. Years later I still watch spongebob from time to time aka nothing else on to watch lol. Sigh I still remember me catching those jelly fishes...good times.
Rhythm Heaven. Was playing it right after I bought it, and someone referred to it as a "counting game" I haven't played it since (And for other reasons, such as the game isn't really that good anyways)
Spongebob Squarepants: Battle for Bikini Bottom. For a licensed title, this is one of the finest because it is a well done collect-a-thon platformer that was still prevalent at that time. Just the Spongebob coat of paint makes me hard to admit to liking it as an adult since Spongebob is considered a kids show, even if I have nostalgia for it when it first premiered.