On a website, l wanted to buy some in- game stuff so l did not wanna give out my real name so l used my real first name but a fake last name. l cant change the info anymore so if l use a credit card to buy the in- game items is that illegal?

ya thats called stealing

l am pretty sure that is illegal because it does not match up with the credit card information, and because it does not match up with that information, l do not think it will even be fully processed and be a successful order.

It is called fraud. If the name you used matches someone else's, it could be identity theft. If you get merchandise or whatever without paying for it, that is theft. You might get paroled, with good behavior, in around 2013-2015.

Chances are when you use the credit card they are going to ask you for the name on the credit card. Otherwise the credit card usually wo not process. It is your credit card right? With your real name on it? And you do plan on paying the bill right? If everything is legit and it really is your card, than you typed in your name wrong.. Simple

As long as the social on the account is your own then l think you're on the good side of law, but that is gray-shaded. If the social on the card is yours and you are the authorized user then you are not stealing but if someone else is name is on the card then that may be a hard thing to prove.