steam
I've just created a new steam account and wanted to activate Half-Live there. Then I got this error message:
When I click on 'Retrieve Account', nothing happens. I am quite sure that I have already activated this many years ago on another account, but I don't remember which account (and which email-address) I used.
When I click on 'See the Steam support site for more information' it seems not to contain helpful information.
I have the original CD and even the receipt.
What can I do now?
If you bought it from Target a few years back, it is likely that you don't actually have a Steam Activation code for the game. However, if you have the game installed on your computer, you can add it to Steam as a non-Steam game in order to make it easier for you to find on your computer.
To do that, click the "Add A Game" button on the bottom left of your Steam window.
From there, click "Add Non-Steam Game" from the list that pops up.
From there, Steam will go through your computer, and give you a list of software that you can add to the menu in your Steam Library. (Note: This does not mean you own Steam versions of the games you add this way.)
Select the games you want to add, and then click "Add Selected Programs". The games you choose will now be available from the Steam launcher.
However, if you don't have the game currently installed, or do not have a way to install the game (such as losing the original CD you have it on), then you will have to re-buy the game.
Steam does (as of Jan. 6, 2013) sell Insaniquarium, so if you have lost the CD and wish to still play the game, re-buying it might be your best bet.
There is no official way to do this, but I wrote a simple script for Mac, that does exactly that: https://github.com/timothybasanov/steamkeysactivator
Script uses AppleScript and could not be ported to Windows or Linux.
Best Answer
Fortunately, because you have the receipt for the game you should be able to basically follow this process with Valve/Steam Support but from a stand point of "I once had this account but don't remember what it was and can prove this game is mine" instead of "I've no longer got this email address". The rest of the process should be the same.
In the instance that you have no proof of purchase for that game, and nothing else linking you to the account, there would be nothing you could do to redeem the game/product a second time.