The patent for loading screen mini-games actually expired Nov. 27th, 2015 if I remember correctly. So I say, by all means, add a mini-game! Then players won't care or notice how long load times are, especially if they are rewarded a prize in the main game as a result!
There's 7 main areas in the game that are all connected. This train get's you from an underground lab to the center of someone's subconscious. inside the train you can talk to some of the passengers. but going to the top of it, there's battles.