AS already said, a high resolution is perfectly manageable by high end desktop computers.
And the reason you found "poor" looking games on mobiles is just that mobile hardware is pretty weak in regards to desktop computers.
Nevertheless have a look at spriter, such a tool should help with your project.
Carefully designed, a triple AAA game is doable in C2, and you're right, C2 is waiting for a killer app.
But the game you're envisioning won't be an easy task. Whatever the framework/engine you do the game in, each platforms you target have their own specificities and limitations and are very different from one another.
You won't be able to have a high end game execute the same on a high end computer and on a smartphone that was released even before the first implementations of HTML5.
For a starter you should just focus on desktop development. This you can be sure, is handled by C2 and will give you the necessary experience and something to show for.