It's 2 separate markets though, people need to remember (even Microsoft) that PC's will always have a place, even if gaming didn't exist, we'd still have PC's.
The issue with making PC only games is that there are so many of them, and getting noticed is nigh on impossible these days, not with Team Meat, Mojang etc making history the whole time.
There is always space for originality, and luck. If you can target all markets at once, then it's a no-brainer... it's like having all your egg's in 1 basket, or having free range eggs, I think that when we release a product, the bigger splash it makes the better, and it's increasingly difficult to make a big splash in 1 single market.
For example, I'm having PC issues - yesterday my new PSU blew, that's 4 days it lasted. Anyway, because of my PC downtime I'm using my mac, and decided to see what Steam could amuse me with, and found Don't Starve. Now - if Don't Starve was PC only, I'd not have bought it - I've seen some YT videos of it of course, but not enough to make me think I'd like it. But, because it's multiplatform I got it, and it's damn good. If it was available on iOS, I'd buy it for that as well, I actually checked.
nonZero, when you try a touch based game and hate it, doesn't that make you want to do something better? - don't you feel like you could come up with a better touch control scheme?
I know that touch control isn't ideal, but it does work well sometimes, but only when the game is well designed around it. I have an iCade controller, which is like a mini arcade cabinet with microswitched joystick, works on a good few iOS games, esp retro games. There are more and more controller options for Android and iOS. My point is that the mobile gaming market is going nowhere, it's a market all on it's own, just like console or PC gaming. People will always want to play games on the bus, and people will always want a big tasty gaming PC. The proof of that is just how many people with a gaming PC have a tablet or smartphone... I'm guessing pretty much all of them. The mobile market is significantly bigger than the PC gaming market... best to try and adapt to these markets I think, there is no point in fighting it. I don't like the way the mobile gaming market has ended up though - paying 69p for a game used to be great, a lot of developers made decent money that way - unfortunately now people don't want to pay 69p for a game, they want it for free, then their kid or someone or them while drunk will go and spend £10 on in-game credits and rubbish. All we can do is adapt as best we can.

I am the one who knocks...
