What to get for kids that don't want anything?

My kids are not human, I swear. They never ask for anything, they have no hobbies, no desires, no ambition. They hide in their rooms all day long and play computer games, watch youtube videos or just sleep.
I have bought them expensive gifts trying to coax them out of their rooms. A scooter, a drone, an underwater camera. They are all still sitting on shelves in their rooms, unopened.
I don't get it.
Should I just buy them a box of cookies and tell them to let me know if one day they want something? maybe if I give them cash they will be forced out? no that won't work because they can just ask mom to buy them something and she will do it.