Yeah it still retains a lot of popularity, enough so that it has had two successful theatrical film releases in the past few years. Yes, its very much children's horror or "gateway horror" is probably a more accurate descriptor. It's a sort of sanitized & pg-13 horror that will act as a gateway to the horror genre. But FNAF spawned an entire genre called "mascot horror" that revolve around "mascot" characters inspired by Chuck E Cheese that began as friendly characters but have been turned "evil" & children are the primary audience for these games. Other games in the genre are Poppy's Playtime, Bendy & the Ink Machine, and many others. It's a genre that's been quite overexposed