Thankfully, it's by Server this time around. Attached to a thing Sega calls a Gamertag, too, so if you cancel your account, your character will still be there when it's re-activated, so long as you didn't get rid of your Sega Gamertag. However, I remember some people saying things about hacked money, which nullified the economy system Sega was going for with the game. I've heard of something people call "Inventory Mods", as well, but both were small scale at the time I heard of them. I've no idea how bad they are now.