   Limiting the number of accounts
  I realize that this is a major issue that even large gaming companies have trouble with, but I would like to know the most popular, most successful, and most effective methods of limiting a player to one account (really, in any environment, however my specific question is in regards to an online game).Considerations:--While limitation is important, having a requirement such as a credit card will alienate those who don't have and/or cannot get one--CD-Keys are meaningless if they are free, and I would rather fund games with official RMT (think MapleStory or GunBound gold shops) than a purchased CD-Key--Difficulty in acquiring an account, such as long waiting times or exhaustive applications, alienates those legitimate users who want their first account--Tracking by PC setup does not limit accounts for those with multiple PC's (I personally have exclusive ownership of four and access to two others), alienates those who upgrade their PCs, and is easily spoofed.--IP numbers are the easiest thing to fakeI would greatly appreciate any suggestions, and I do know that no solution wont alienate or annoy at least some players.  Thank you for taking the time to read this thread, and thanks once more to anyone who comments.   
  Maybe the question is why you don't want players with multiple accounts?  You make the same amount of money either 2 people buy your game, or 1 person buy your game twice.  The best method is probably removing the incentive to have multiple accounts, or raise the cost (fees/requirements) so the benefits of multiple accounts are less attractive.  Lots of people create multiple gmail/yahoomail accounts.  Now if they charge, say $10, per account per month, alot of those people would disappear.  But some people would spend the money for legit reasons (business/personal accounts..etc).   ;  First of all, IP addresses aren't so easy to fake outright [in some instances they can change, and you can use a proxy to hide behind, but you can't 'fake' your IP], but even tracking IP addresses with the assumption that they will remain static can include some collateral damage [you ban me, and my roommate looses their account too, if we share a connection.  Or maybe i have access to a public machine].  The fact of the matter is that you can't differentiate between one individual and another at the same machine, and rely on an honest user to be able to differentiate one machine from another.IP address tracking and account ID's are rather common solutions to this problem, though the use of this information is rarely to restrict access to 'legal' users, but instead to assert that punishments stick in the case of users who have violated the rules [which is an instance in which the collateral damage associated with this sort of tracking becomes often times acceptable].  Finger printing versions and tracking PCs is only a reasonable answer if you refuse to allow the instance of a single user with a single account who uses that account on multiple machines.  MANY people, myself included, have multiple credit cards, and using those as identification will not assert uniqueness among the card holder.  And if you ask for any sort of real-life unique identifier, like a social security number, many people are more than willing to outright lie if it gets them what they want, and you're left with little in the way of resources to assert the validity of information that exists outside your game.You cannot assert 100% that a user does not own multiple accounts, even with the use of credit card information, or real-life ID's, or anything else, if your user base has sufficient resources and technical know-how.  Your best defenses should be concentrated against your 'average' user, who does not have vast resources to buy extra computers for every account they might want, and who doesn't have the technical know-how to disassemble your network packets and reassemble them as needed.Finger print software, keep user ID's, and use the typical methods to scan for multiple instances of the game.  All this is only useful though if you wish to restrict the use of multiple instances of the *same* game/account/whatever [as in, buy one CD, burn 10,000 of them].In short, you're choosing to fight a battle you've already lost.   ;  CC, Fees, Removing reasons to have multiple accounts, photo id, One Roleplay server i looked at once, required you to call them upbut considering i live in AUS i wasn't paying overseas phone calls just topay a RP server, constant checks for simliar data, login timesJust random idea's ive seen, never seen one really workFee's are prob most effective, if there paying for two accountsand can't login both on the same ip address, better value for yourself.   ;  Like someone allready said, I think it is more important to know why you dont want anyone to have multiple accounts.If you dont want players to help themself with their own accounts, transfering ingame gold to other charakters then I would suggest investigating all gold transfers and banning them really fast. Make some news about it and most people will stop trying that.Certainly you can never stop everyone from doing such things.Or thing about if you really need to limit the players to one account.   ;You can't.Without invading the privacy, gratuity or anonymity of your users (paying accounts, credit card numbers, PC identification), you cannot make automatically the difference between a "first account" and "additional account", and will thus have to deal with the two in the same way. You can make it harder by using IP checks (one account per IP), mail checks (one user per address), computer hardware (one account per hardware), but this is ultimately falsifiable and will only deter the unmotivated players. This does only leave the motivated players, and those will usually try to win big through their tactics so monitoring whatever a player can gain from another biased trades will allow you to catch these.   ;  Here is my take on the issue:Every player is allowed one login account.  (Player contact information is collected here.)Each login account is allowed X number of characters.  (X >= 2)True, this gives them multiple characters, but since they're linked by login you can limit them to only one on-line at a time.  Where I see this system working is that people will find a single login easier to remember for accessing all their characters than a one-to-one solution.Of course, as others have said, anyone who wants to bust through your restrictions will ultimately find a way.  If this disrupts your game, than you might want to re-examine where the problem truly is...The customer is always right.   