Ask HN: 10 year old girl with creative stop motion art wants to program a game

At my son's birthday party today, a friend's daughter said to me 'you know how to program games and apps. I have some ideas and I want to program a game'. She showed me some really wicked stop-motion video she created with hand-drawn graphics (sharks hunting sharks underwater). I asked about her primary goal - it is mobile phones (1), tablets (2), PC(3), not consoles. Her dad would set up a Linux PC for her, though she can use her mom's Windows PC, too.

Any people with experience here - what would be the easiest way for her to start?