Nights are playable Levels of the game, if the player complete all Nights player will "win" the game.
Night 1 is the first playable night of Five Nights at Treasure Island. Compared to the later nights, this night is relatively easy and serves mainly as an introductory stage that accustoms the player to the game's mechanics, allowing the player (if new) to get used to how to survive, and to get use to the building's whereabouts.
Night 2 is the second playable night of Five Nights at Treasure Island, as well as the last playable night in the old demo. This night starts immediately increasing the difficulty, as Photo-Negative Mickey will start to get more active and Dark Oswald becomes a threat from this point onward. Disembodied and The Face are also active this night and one of them can also sometimes appear in the Office, effectively multiplying the number of potential threats to watch out for.
Night 3 is the third night of Five Nights at Treasure Island. Unlike the previous two nights this night is cut short to 3AM, which the player will be sent to Pirate Caverns, which that is where the Player will have to survive against The Face and Undying. Photo-Negative Mickey and Dark Oswald are more aggressive than they were in the previous night. The Face and Disembodied also have a higher chance of entering the Office this night compare to the previous night. Acephalous, Suicide Mouse and Hourglass will be active on this night as well. On rare cases Pluto may enter the Office.
The Pirate Caverns is a special area accessed as the second half of Night 3. This area is where Undying will start. When the player enters Pirate Caverns, the game style changes to a point-and-click type of adventure game where the player clicks to go to other areas in the cavern. The player can enable a flashlight by pressing the space bar. The Face will also be a threat in this area.
Night 4 is one of the nights in Five Nights at Treasure Island: Found, which unlike Night 3, this Night will not End at 3AM, Night 3 was the only night to end at 3AM. This night drastically increases the difficulty as most of the characters become active at this point. Acephalous, Suicide Mouse and Hourglass are much more active this night as well as all the previous suits. Purity becomes a threat this point on and may continuously enter the Office in a short period of time. Photo-Negative Minnie and Willy are also active this night, as well as Daisy Duck sometimes. The player should also be cautious about Oswald as if not watch carefully he can easily catch the player off guard. The player must also constantly check Meat Freezer to slow down Undying's movement, as when it enters the Office, the player have no option but turn off the power.
The only suits and Humanoids that are active on this Night are Photo-Negative Mickey, Dark Oswald, Disembodied, Suicide Mouse, Acephalous, Hourglass, Pluto, The Face, Photo-Negative Minnie, Oswald, Daisy, Purity, Undying, Willy and Slester.
The only suit active on this night will change depending on the ending. If the player has not met the requirements for the True Ending, Corruptus will be the only active suit this night. If the player has, True Mickey will be the only active suit.
The only suits and Humanoids suspected to be active on this Night is your choice.
The only suits and Humanoids suspected to be active on this Night are the same as Night 5.
Infinite Night was a never-ending night where the Suits and Humanoids AI difficulty will get higher as the night goes on. As suggested by the name, the night will never end. This is a mode where the player must try and survive as long as possible to get a high score.