I think it'd be cool to design a virtual city with easy bike/pedestrian access to nearby shops, schools and other amenities while minimizing car dependency (as therefore the pollution, noise, parking issues and noise that come with it).
Do you know any good city builder games for this?
Growing genetically modified pigs with human-like hearts to save human lives? The ethics of that are a bit complicated, but from a STEM perspective it's a really fascinating idea. What a time to be alive.