A lot of the comics in CHAINMAIL BIKINI are women's reminiscences on what gaming meant to them as kids and teens, so I definitely think that stuff would be appropriate to that age group. Probably the most adult-themed comic is Elizabeth Simin's lovely story about using Guitar Hero to cope with her OCD in college. That one does have the word "fuck," as well. You can read a sample page here:
Still, I think it would be fine for a mature 12-year-old.