Re: Can't register game on TheSims3.com - Steam-issued code apparently already used
@RynTea When did you buy the game from Steam? People don't get a serial code anymore due to a loophole with EA Play that needed to be closed, so if you bought the game in the last year or so, you wouldn't have one either. Point is, if you look at the registry entry for Sims 3, do you see a 20-character code, or just some field that says "null" or similar?
From your wording, I can't tell whether you do have a code and it's already been used, or you don't have a proper code and the "already been used" is just the EA support rep's interpretation of the error code you're seeing. Normally, when you enter a code that's already been used, the error message says exactly that.
What you can do, if you bought the game too recently to have received a code, is contact EA customer support and ask that the game be added to your Origin account. You'll need to provide proof of purchase and ownership: screenshots of the email receipt and your Steam library with your username and Sims 3 showing should do it.
https://help.ea.com/en/contact-us/
If you don't get anywhere with EA support this time around, please let me know when you bought the game and whether you have something resembling an actual code. You don't need to post the code; just confirm it's 20 characters and appears in the correct portion of the registry.