How to get there?
get off at the metro station called Taipei City Mall, Exit 17 / 18 /19

What can I buy there?
It is not as rich as other malls that I had the pleasure of exploring in Hong Kong, but I think it is the absolute best in Taipei. You will find:
- video games (new and retrogaming)
- tons of action figures and gashapons
- manga (few)
- a good selection of arcades
- random otaku stuff