Thanks for reporting this. The game works on my Android tablet (Chrome mobile), but it is not really optimized for mobile, yet (dialog and city panel are not responsive). I will try to find someone with an iPad and look into this.
Thank you for the feedback! Custom quizzes would be really nice to have and they are probably quite easy to add. In fact, I already have the tools to generate custom city collections:
How do I know what I'm looking for?