The fangame graveyard is filled with ambitious projects that never saw the light of day.

Young developers often want their first project to be a Free-Roam, Unreal Engine 5 masterpiece with voice acting and 12 different mechanics. That is a recipe for cancellation. My advice is to start with "One Night." Make a game that is just one night long. If you can polish one night to perfection, then you can scale up. If you can't finish one night, you definitely won't finish five.

Many young fans want to be the "Idea Guy." They write the lore, design the characters on paper, and then look for people to "make it for them. The reality is Nobody will make your game for you. You must learn a hard skill. Learn to model in Blender, or learn to code in Clickteam/Godot/Unity. The most successful fangames are led by people who got their hands dirty in the engine.

There is a dopamine hit that comes from posting a Game Jolt page with a teaser image. But once you announce the game, the clock starts ticking and the pressure builds. I would ask you to not announce the game until you have a playable alpha. Develop in the shadows. If you announce a game and then don't have updates for 6 months, people lose interest and you lose motivation.

When it comes to the game atmosphere and scare factor, new developers often think "Scary = Loud Noise. I would advice you to study why classic FNaF was scary. It wasn't the scream; it was the silence before the scream. It was the camera static. It was the feeling of being watched. Spend more time on sound design (ambience, footsteps, fan noise) than on the jumpscare animation.

I also often thought maybe my game was too simplistic, TRTBN was partially criticized for it too. But it still was successeful because of that. Simple is better than broken. A game with one mechanic that works perfectly is infinitely better than a game with five mechanics that are buggy and confusing. Don't add features just to be "different." Add features that make the game fun.

Now the last part. This is the hardest one. The last 10% of development takes 90% of the time.
You will hate your game by the time you are finishing it. You will look at it and think it's ugly. Finish it anyway. A released "okay" game is better than a perfect game that stays on your hard drive forever.

Please take time to make everything, take time to learn, to build skill and once you happy with it, release it! It doesn't have to be perfect, TRTBN wasnt. But it worked. And i wish luck for you too!