Cracking online games is totally different from cracking non-online games, and most online game cracks don’t exist or don’t work because the game company has more control over knowing who is or is not a legitimate user.
With non-online games, one can crack the executable to ignore any CD detection or ignore any call-home code. As long as the game doesn’t rely on getting assets from the company’s server, you should be able to play the game with no problems.
It’s when you try to get assets from their servers that it becomes improbable/impossible to crack. First off, you usually need to log in, and when they catch a logged in user trying to do suspicious things (too many connections in a short amount of time, for instance, is a good sign that the user is using a third party program to attempt something, which goes against pretty much all game rules and terms you agreed to when signing up), they axe the account and may note your IP, making it harder for you to keep cracking it. Next, most online games are fueled by subscription fees, where no pay = no play. So now you have to fake a credit card transaction just to be able to keep cracking away at the core game. Not gonna happen.