I played a game like this before. The whole journey took about 6 hours to complete. Realizing who I was interacting with was one of the best moments I've had playing a video game.
Edited to add: I think I've played two games where the bots turned out to be people. The second game was much longer, and I never finished it - I only learned that the bots were people from a YouTube video later on.
Riot Games did this one year for April Fools in League of Legends. Normally you can play a 5v5 match against other players, beginner bots, or intermediate bots.
For April Fools, they rolled out "Advanced Bots", which were actually another group of 5 humans, but with their username replaced with "<Character> Bot". Word got out pretty fast, but it was super funny queuing up for a game you'd normally win easily and being surprised at how smart those bots have gotten...
I don’t remember which iteration it was, but there is a game in the Dark Souls series where one of the bosses is a player that invades your game to be the boss.
It’s a cool twist on the PvP of the game where you can be invaded by a player at almost any time but you can usually opt out of the PvP but this particular encounter is needed to progress.
