You can[t play the game offline anymore. There is a bug the says you are disconnected from internet, but you are. The multiplayer levels sometimes makes you play against very powerfull players, making it tottally unfair. Recently, the devs are nerfing power at every single update. You feel It everytime you try to play a campaign mission or the daily missions (bombarding, protect and assault). Well, simply you have to upgrade everything you can just to do no progress, but to play just like you used to play. They are pushing players to spend more and more money in order not to fell powerless.