The recent Act of Aggression is a inofficial successor of C&C Generals. I just had time to play it for a few hours, but it seems to be almost as good as Generals. Though it's more complex (more unit upgrades, more ressources) and unlike Generals the building part of the game is less advanced: it limits buildings to a grid and building cannot be placed everywhere.
And Cities Skylines is the best city building simulation. It was a big surprise that a small team managed to create such a superior game. EA's SimCity 2013 with fake simulation was a failure.
