My top game should be Xenoblade Chronicles X, and any less than 800 hours would be false. I don't think I really played any other title (besides FIFA 13) for more than 100 hours.
My bet with The_Liquid_Laser: I think the Switch won't surpass the PS2 as the best selling system of all time. If it does, I'll play a game of a list that The_Liquid_Laser will provide, I will have to play it for 50 hours or complete it, whatever comes first.