I think the fact that it is barely a game with a low entry barrier (compared to "turn based tactical video game" like most other pokemon games are) with a massi

I think the fact that it is barely a game with a low entry barrier (compared to "turn based tactical video game" like most other pokemon games are) with a massive following who don't really play video games or have ever watched the anime but know who Pickachu or what a Jrigglypuff is (nerd-credit rating requirements, mention in BazingaBang or "hip" stuff like those) was an important factor too.