I know not everyone gets their PC indie games from Steam, but their very pro-indie store design certainly helps keep the market vibrant. They often feature games from tiny companies in front-page promo spots, they promote indie packs in their sales, and their 'you may also like...' suggestions don't seem to shy away from obscure 'long tail' titles. All in all, discovery is pleasant and easy.

I buy very few games on Steam these days. I dislike DRM, so I vote with my wallet, and spend most of my gaming budget supporting DRM-free games on Gamersgate.

Yeah, perhaps I was wrong to focus so much on Steam in my comment. Gamersgate, GOG and Green Man Gaming (to name a few) also do a fine job of drawing attention to less mainstream titles.

* PC games can charge a lot more. On mobile, users will balk at anything that costs more than .99 cents. If you want to charge $5, you have to have a pretty amazing game (like, Zelda-level), and even then people will complain.

* Lots, lots more competition from crappy spammy games that flood out the good ones.