glez13 :
Command & Conquer and Age of Empires need a reboot or return.
Obviously a lot of RTS fans in this thread, but it's pretty amazing that two long-running giants of the genre have been more or less completely forgotten. I'll go a bit further and say what I'd like to see in each:
Command & Conquer: Get back to the reality-based roots of the game. The original, and Red Alert, were both strongly steeped in real combat. It seemed the more tiberium-crazy they got, the worse. For a reboot, I think they could really focus on taking a Company of Heroes vibe and mixing it in with the slightly-oddball themes like you saw in Generals. Keep it just on the edge of realism and believability.
Age of Empires: I really feel like the issue with Age of Empires is that advanced controls don't scale well with large unit sizes. Either the units have to be simple (Ashes), or you have to aggregate them (Total War series). Given AoE's historical roots, it'd be pretty awesome if they went in the Total War direction. The hardwareis about at the point where it's feasible for the player to build a fortress city in-game, build up an army (with only a few units with large unit sizes), and fight in a semi-realistic 3D mockup map.