It is certainly possible, Conquer doesn`t use shaders so it isn`t that intensive graphically, it could be done easily in OpenGL ES for both iPhone and Android. Handling all the game files etc. could be a problem, but if it`s going to be played on mobile then the resolutions can be reduced, maybe poly-count as well, it`s easily doable.
To strengthen my argument, I`d like to show you this :
It`s a much more intensive context than CO.
p.s. Learning graphics programming will be a ***** though.