I'm an unapologetic Five Nights at Freddy's fangirl. I've played all the games and scoured the Wiki for fan theories. I watch Markiplier's playthroughs and laughed at all of Crazy Boris's animations. I've cosplayed as the series' mysterious killer, Purple Guy, and received many hugs from kids, which baffles and worries me.
But part of being a responsible fan is realizing that everything can use improvement, and that sure as heck goes for the Five Nights at Freddy's series, too. It's obviously not possible to get everyone on board with the antics of Freddy and his Friends (some folks simply cannot digest jump scares, and for good reason), so making improvements doesn't necessarily mean fiddling too much with the games' core mechanics. For instance:
The games need better mobile ports
To date, FNAF titles are released on PC (via Steam) and mobile (iOS and Android). The releases are usually very close to each other, so fans have their choice of playing on a desktop or taking Freddy to bed with them. The mobile versions of the game also tend to be cheaper than the PC versions ($2.99 USD versus about $7.99 USD).
You really do get what you pay for, however. The mobile FNAF games skimp on porting the PC versions' content -- and let's be honest, the FNAF titles are not content-heavy to begin with. Story exposition seems to suffer the most. For instance, the Atari-style mini-games that set up the story in Five Nights at Freddy's 4 are, at the time of this writing, absent from the mobile version of the game.
Is it worth sacrificing FNAF mobile's atmosphere to strip a few bucks off the price tag? The reason the series is so popular is because all its elements work in tandem to present something engaging and horrifying.
There should be a side adventure game, or some other method of genre-hopping
The aforementioned Atari-style mini-games, which first appeared randomly in Five Nights at Freddy's 2, have become almost as iconic to the series as its jump scares. The re-imagining of the games' cast and environments as purposefully slow, chunky sprites makes for some surprisingly creepy storytelling.
Series developer Scott Cawthon has made several games across several genres, so it goes without saying that he'd have little trouble putting together a side-project based around the FNAF franchise. An adventure game or RPG would be a great way to expand on the series' lore, especially if done in the retro style Cawthon seems to love.
Jump scares and survival horror are nice and all, but variety is a tasty pizza topping.
Invest in some better bug testing before release
At some point during Five Nights at Freddy's 3's development, Scott Cawthon revealed that his games' primary testers are his kids. Aw, bless.
Nobody doubts Cawthon's work ethic: The man is a machine, and he seemingly enjoys putting the games together by himself with some added assistance from his family. That's fine, except the earliest review of new FNAF games are usually coupled with extensive bug reports. Said bugs are always fixed in good time, though it'd obviously be better if they simply didn't exist at all.
Prominent YouTubers usually get to play new FNAF games before they're released to the public; maybe some dedicated bug testers could get their hands on the game early, too.
Or maybe Cawthon should consider sticking to a promised release date at least once. FNAF 4 was supposed to come out on Halloween 2015. Then it was promised for August 8. Then it hit Android and PC on July 23. The FNAF series is about in-your-face surprises, but that's time that could go towards a little extra bug testing.
Keep trying new things with the old formula
One of the most common criticisms lobbed at the FNAF series is, "The games are all the same!" It's an easy judgement to make, but fans of the series know there are small but important differences between the games. For instance, whereas FNAF 3 requires you to make heavy use of visual cues in order to stay safe, survival in FNAF 4 gets rid of the series' now-familiar security camera feed and forces us to rely almost wholly on audio cues.
While listening for clues in the dark is some super-stressful work (though Cawthon took mercy on us and made said clues a bit easier to hear in an update), changing up the game's formula keeps us on our toes. Keep doing it, Scott -- and maybe also consider that earlier suggestion about a side-story based in another genre? Eh?
Tie up some loose ends before making new plot threads!
Some of these suggestions are lofty, but this one is really reaching for the moon.
With every question Cawthon seemingly answers about the child murders that drive FNAF's story, six new questions are born. Even FNAF 4, which first seems like a crystal-clear narration about the Bite of '87 mentioned in the first game, can't help but add little moments that all but explicitly snicker, "or is it?"
It's maddening, to say the least. Then again, where would we be if FNAF's young fans didn't have vague story hints to pore over for hours on end? They'd be roaming the neighborhood and getting into trouble. Eating pizza. Taking selfies with Chuck E Cheese animatronics. Sneaking smokes with the half-busted members of the Rock-afire Explosion.
Maybe things are better this way.