If they have tiers of units that can be used throughout and not just how advanced you are in the games timeline, or tons of up-gradable tech trees, and maybe more control over unit formations - great. It just seems like the old build, swarm, and conquer no longer holds my interest for very long. Even the Total War series like Attila got boring as hell with lazy linear tech trees, crap AI, and a campaign map that didn't offer much in the end except random message spam of events.