Camera zooming

This was Plus' main mechanic according to Phil. The way it worked was if you saw an animatronic on a camera, you'd have to zoom in on them to lock them in place. They would be aware of you doing this, and would try and hide at the sides of cameras to avoid you catching them. This would technically make it possible for you to completely freeze one of the characters, possibly forming a variety of strategies for gameplay depending on the mechanics of each animatronic, although it should be noted that it would only be usable one camera at a time.

Helpy

Phil said he had a vision for helpy where he'd be in a "low-poly training tape" to teach you about the key mechanics of the game, but cutscenes weren't gonna be in plus so ¯\_(ツ)_/¯

Character designs

According to Phil, the designs of the Plus animatronics were recreations of the original designs, but with the features Phil thought were most noteworthy about the original being more exaggerated (Bonnie's uncanny stare, foxy's tattered clothing, chica's hanging jaw and freddy's fazaura. This means that designs in the "plus" style should emphasise the defining features of the robot, instead of just adding clothing.

Character events

Each night would have a character event, apart from night 1.

2nd night was bonnie, 3rd was chica, 4th was foxy, 5th was freddy, and we can assume the 6th might've been the puppet.

Chica's and Foxy's were the most elaborated on, and they would've featured a ton of animation which took Phil months to do.

On Night 3, Chica would start in backstage sitting down on the table facing the camera, and during the night the intern would call the player saying that the day before a guy (potentially William) entered the restaurant and Chica lashed out at him. She was deactivated and put into the backstage. The intern said that if she ever reactivated and started wandering around in the night, we would need to let staff know the next day as she shouldn't be. After this, chica would start "convulsing" violently, and would try ripping off her jaw/beak from her head. The jaw was glued to the front however, making the outcome a lot messier, and for the rest of the game, her jaw would be hanging limp from her head.

She would also become a lot more aggressive, and would target the electrical box, draining your power if you didn't zoom in on her.

Once escaping his stage, Foxy would rush to a random camera on the West or East side of the restaurant and you would have to zoom in on him on said camera to force him to go back into his cove and not to either side of your office. On some cameras, he would be very hard to see, similar to Springtrap in fnaf 3. He would become a lot more "desperate" on night 4, and would have an animation of him escaping pirates cove and rushing towards the exit, banging his head against the metal grate, crying like a mix of fox and a soon to be murdered child. This could call back to how he died.

Lastly, Phil stated that he wanted Freddy to be more "in the spotlight" for the game. His mechanics aren't elaborated on much, but I've heard some people say Phil said he'd try lifting up the door when you try closing it on him, so that might be interesting.