What games does MS need to bring to WP?

I am talking about MS as a first party dev.

They released some amazing games like PGR and Audiosurf for Zune HD. Why the hell haven't they brought those goodies over to WP8?

It's mind boggling that they still haven't made a Halo mobile game. Look at how NOVA is doing in other platforms.

MS is one of the gaming powerhouses and all they can do when it comes to free games is Minesweeper, Sudoku, Flowerz etc? I mean what the fuck.