I went ahead and did a mini-review on Steam.

http://steamcommunity.com/id/MarioFanaticXV/recommended/337150/

What do you guys think?

What features do you want on the PC?   Handelabra seems fairly open to listening to ideas and criticism. Obviously, MigrantP is pretty active on these forums too. Though being at Pax East will slow down any response.  

Being able to hit "Enter" for "Yes" seems pretty standard, but enter has no function as far as I can tell. Also, it feels odd that I can't use the arrow keys to scroll. They could also imlement other keyboard shortcuts pretty easily; such as Backspace for the rewind feature (or Ctrl+Z since that's often asigned to Undo), and maybe something for the "check powers" button. Or even just bindable keys.

And an interface that allows one to use a gamepad would be a nice option as well- it's just the fact that it's 5 USD more than the tablet version yet feels exactly like it would if I bought the tablet version and used an android emulator to play it that bothers me- if it's going to be more expensive, it should have more features, especially since the development costs for the PC are definitely cheaper than they are for iOS with all of Apple's bureaucracy (can't speak about how it compares to Android, not sure about that one, I know that also beats out iOS though).

They do plan to implement keyboard shortcuts.

This is my intuition, too, but … I wonder.  How does one price these things? 

Despite my sense that the same game "should" cost the same on different platforms, I have disparate impressions of how much games on different platforms "should" cost: My intuitiion for PC is that $15 is relatively INexpensive, but my intuition for an iOS or Android app is that $10 is pretty expensive. 

Economics suggests that the best price is the one on the demand curve that maximizes profit, and maybe that's what is going on here. They've priced the game differently on different platforms because the demand curves on those platforms are different.

It's also possible that Steam demands a higher portion of proceeds than the other options, I have no idea what any of them charge so I can't be certain, but that would make the most sense to me.